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diff --git a/coq.html.markdown b/coq.html.markdown new file mode 100644 index 00000000..115d9ff8 --- /dev/null +++ b/coq.html.markdown @@ -0,0 +1,478 @@ +--- +language: Coq +filename: learncoq.v +contributors: + - ["Philip Zucker", "http://www.philipzucker.com/"] +--- + +The Coq system is a proof assistant. It is designed to build and verify mathematical proofs. The Coq system contains the functional programming language Gallina and is capable of proving properties about programs written in this language. + +Coq is a dependently typed language. This means that the types of the language may depend on the values of variables. In this respect, it is similar to other related languages such as Agda, Idris, F*, Lean, and others. Via the Curry-Howard correspondence, programs, properties and proofs are formalized in the same language. + +Coq is developed in OCaml and shares some syntactic and conceptual similarity with it. Coq is a language containing many fascinating but difficult topics. This tutorial will focus on the programming aspects of Coq, rather than the proving. It may be helpful, but not necessary to learn some OCaml first, especially if you are unfamiliar with functional programming. This tutorial is based upon its OCaml equivalent + +The standard usage model of Coq is to write it with interactive tool assistance, which operates like a high powered REPL. Two common such editors are the CoqIDE and Proof General Emacs mode. + +Inside Proof General `Ctrl+C Ctrl+<Enter>` will evaluate up to your cursor. + + +```coq +(*** Comments ***) + +(* Comments are enclosed in (* and *). It's fine to nest comments. *) + +(* There are no single-line comments. *) + +(*** Variables and functions ***) + +(* The Coq proof assistant can be controlled and queried by a command language called + the vernacular. Vernacular keywords are capitalized and the commands end with a period. + Variable and function declarations are formed with the Definition vernacular. *) + +Definition x := 10. + +(* Coq can sometimes infer the types of arguments, but it is common practice to annotate + with types. *) + +Definition inc_nat (x : nat) : nat := x + 1. + +(* There exists a large number of vernacular commands for querying information. + These can be very useful. *) + +Compute (1 + 1). (* 2 : nat *) (* Compute a result. *) + +Check tt. (* tt : unit *) (* Check the type of an expressions *) + +About plus. (* Prints information about an object *) + +(* Print information including the definition *) +Print true. (* Inductive bool : Set := true : Bool | false : Bool *) + +Search nat. (* Returns a large list of nat related values *) +Search "_ + _". (* You can also search on patterns *) +Search (?a -> ?a -> bool). (* Patterns can have named parameters *) +Search (?a * ?a). + +(* Locate tells you where notation is coming from. Very helpful when you encounter + new notation. *) +Locate "+". + +(* Calling a function with insufficient number of arguments + does not cause an error, it produces a new function. *) +Definition make_inc x y := x + y. (* make_inc is int -> int -> int *) +Definition inc_2 := make_inc 2. (* inc_2 is int -> int *) +Compute inc_2 3. (* Evaluates to 5 *) + +(* Definitions can be chained with "let ... in" construct. + This is roughly the same to assigning values to multiple + variables before using them in expressions in imperative + languages. *) +Definition add_xy : nat := let x := 10 in + let y := 20 in + x + y. + + +(* Pattern matching is somewhat similar to switch statement in imperative + languages, but offers a lot more expressive power. *) +Definition is_zero (x : nat) := + match x with + | 0 => true + | _ => false (* The "_" pattern means "anything else". *) + end. + + +(* You can define recursive function definition using the Fixpoint vernacular.*) +Fixpoint factorial n := match n with + | 0 => 1 + | (S n') => n * factorial n' + end. + + +(* Function application usually doesn't need parentheses around arguments *) +Compute factorial 5. (* 120 : nat *) + +(* ...unless the argument is an expression. *) +Compute factorial (5-1). (* 24 : nat *) + +(* You can define mutually recursive functions using "with" *) +Fixpoint is_even (n : nat) : bool := match n with + | 0 => true + | (S n) => is_odd n +end with + is_odd n := match n with + | 0 => false + | (S n) => is_even n + end. + +(* As Coq is a total programming language, it will only accept programs when it can + understand they terminate. It can be most easily seen when the recursive call is + on a pattern matched out subpiece of the input, as then the input is always decreasing + in size. Getting Coq to understand that functions terminate is not always easy. See the + references at the end of the article for more on this topic. *) + +(* Anonymous functions use the following syntax: *) + +Definition my_square : nat -> nat := fun x => x * x. + +Definition my_id (A : Type) (x : A) : A := x. +Definition my_id2 : forall A : Type, A -> A := fun A x => x. +Compute my_id nat 3. (* 3 : nat *) + +(* You can ask Coq to infer terms with an underscore *) +Compute my_id _ 3. + +(* An implicit argument of a function is an argument which can be inferred from contextual + knowledge. Parameters enclosed in {} are implicit by default *) + +Definition my_id3 {A : Type} (x : A) : A := x. +Compute my_id3 3. (* 3 : nat *) + +(* Sometimes it may be necessary to turn this off. You can make all arguments explicit + again with @ *) +Compute @my_id3 nat 3. + +(* Or give arguments by name *) +Compute my_id3 (A:=nat) 3. + +(* Coq has the ability to extract code to OCaml, Haskell, and Scheme *) +Require Extraction. +Extraction Language OCaml. +Extraction "factorial.ml" factorial. +(* The above produces a file factorial.ml and factorial.mli that holds: + +type nat = +| O +| S of nat + +(** val add : nat -> nat -> nat **) + +let rec add n m = + match n with + | O -> m + | S p -> S (add p m) + +(** val mul : nat -> nat -> nat **) + +let rec mul n m = + match n with + | O -> O + | S p -> add m (mul p m) + +(** val factorial : nat -> nat **) + +let rec factorial n = match n with +| O -> S O +| S n' -> mul n (factorial n') +*) + + +(*** Notation ***) + +(* Coq has a very powerful Notation system that can be used to write expressions in more + natural forms. *) +Compute Nat.add 3 4. (* 7 : nat *) +Compute 3 + 4. (* 7 : nat *) + +(* Notation is a syntactic transformation applied to the text of the program before being + evaluated. Notation is organized into notation scopes. Using different notation scopes + allows for a weak notion of overloading. *) + +(* Imports the Zarith module containing definitions related to the integers Z *) +Require Import ZArith. + +(* Notation scopes can be opened *) +Open Scope Z_scope. + +(* Now numerals and addition are defined on the integers. *) +Compute 1 + 7. (* 8 : Z *) + +(* Integer equality checking *) +Compute 1 =? 2. (* false : bool *) + +(* Locate is useful for finding the origin and definition of notations *) +Locate "_ =? _". (* Z.eqb x y : Z_scope *) +Close Scope Z_scope. + +(* We're back to nat being the default interpretation of "+" *) +Compute 1 + 7. (* 8 : nat *) + +(* Scopes can also be opened inline with the shorthand % *) +Compute (3 * -7)%Z. (* -21%Z : Z *) + +(* Coq declares by default the following interpretation scopes: core_scope, type_scope, + function_scope, nat_scope, bool_scope, list_scope, int_scope, uint_scope. You may also + want the numerical scopes Z_scope (integers) and Q_scope (fractions) held in the ZArith + and QArith module respectively. *) + +(* You can print the contents of scopes *) +Print Scope nat_scope. +(* +Scope nat_scope +Delimiting key is nat +Bound to classes nat Nat.t +"x 'mod' y" := Nat.modulo x y +"x ^ y" := Nat.pow x y +"x ?= y" := Nat.compare x y +"x >= y" := ge x y +"x > y" := gt x y +"x =? y" := Nat.eqb x y +"x <? y" := Nat.ltb x y +"x <=? y" := Nat.leb x y +"x <= y <= z" := and (le x y) (le y z) +"x <= y < z" := and (le x y) (lt y z) +"n <= m" := le n m +"x < y <= z" := and (lt x y) (le y z) +"x < y < z" := and (lt x y) (lt y z) +"x < y" := lt x y +"x / y" := Nat.div x y +"x - y" := Init.Nat.sub x y +"x + y" := Init.Nat.add x y +"x * y" := Init.Nat.mul x y +*) + +(* Coq has exact fractions available as the type Q in the QArith module. + Floating point numbers and real numbers are also available but are a more advanced + topic, as proving properties about them is rather tricky. *) + +Require Import QArith. + +Open Scope Q_scope. +Compute 1. (* 1 : Q *) +Compute 2. (* 2 : nat *) (* only 1 and 0 are interpreted as fractions by Q_scope *) +Compute (2 # 3). (* The fraction 2/3 *) +Compute (1 # 3) ?= (2 # 6). (* Eq : comparison *) +Close Scope Q_scope. + +Compute ( (2 # 3) / (1 # 5) )%Q. (* 10 # 3 : Q *) + + +(*** Common data structures ***) + +(* Many common data types are included in the standard library *) + +(* The unit type has exactly one value, tt *) +Check tt. (* tt : unit *) + +(* The option type is useful for expressing computations that might fail *) +Compute None. (* None : option ?A *) +Check Some 3. (* Some 3 : option nat *) + +(* The type sum A B allows for values of either type A or type B *) +Print sum. +Check inl 3. (* inl 3 : nat + ?B *) +Check inr true. (* inr true : ?A + bool *) +Check sum bool nat. (* (bool + nat)%type : Set *) +Check (bool + nat)%type. (* Notation for sum *) + +(* Tuples are (optionally) enclosed in parentheses, items are separated + by commas. *) +Check (1, true). (* (1, true) : nat * bool *) +Compute prod nat bool. (* (nat * bool)%type : Set *) + +Definition my_fst {A B : Type} (x : A * B) : A := match x with + | (a,b) => a + end. + +(* A destructuring let is available if a pattern match is irrefutable *) +Definition my_fst2 {A B : Type} (x : A * B) : A := let (a,b) := x in + a. + +(*** Lists ***) + +(* Lists are built by using cons and nil or by using notation available in list_scope. *) +Compute cons 1 (cons 2 (cons 3 nil)). (* (1 :: 2 :: 3 :: nil)%list : list nat *) +Compute (1 :: 2 :: 3 :: nil)%list. + +(* There is also list notation available in the ListNotations modules *) +Require Import List. +Import ListNotations. +Compute [1 ; 2 ; 3]. (* [1; 2; 3] : list nat *) + + +(* +There are a large number of list manipulation functions available, including: + +• length +• head : first element (with default) +• tail : all but first element +• app : appending +• rev : reverse +• nth : accessing n-th element (with default) +• map : applying a function +• flat_map : applying a function returning lists +• fold_left : iterator (from head to tail) +• fold_right : iterator (from tail to head) + + *) + +Definition my_list : list nat := [47; 18; 34]. + +Compute List.length my_list. (* 3 : nat *) +(* All functions in coq must be total, so indexing requires a default value *) +Compute List.nth 1 my_list 0. (* 18 : nat *) +Compute List.map (fun x => x * 2) my_list. (* [94; 36; 68] : list nat *) +Compute List.filter (fun x => Nat.eqb (Nat.modulo x 2) 0) my_list. (* [18; 34] : list nat *) +Compute (my_list ++ my_list)%list. (* [47; 18; 34; 47; 18; 34] : list nat *) + +(*** Strings ***) + +Require Import Strings.String. + +(* Use double quotes for string literals. *) +Compute "hi"%string. + +Open Scope string_scope. + +(* Strings can be concatenated with the "++" operator. *) +Compute String.append "Hello " "World". (* "Hello World" : string *) +Compute "Hello " ++ "World". (* "Hello World" : string *) + +(* Strings can be compared for equality *) +Compute String.eqb "Coq is fun!" "Coq is fun!". (* true : bool *) +Compute "no" =? "way". (* false : bool *) + +Close Scope string_scope. + +(*** Other Modules ***) + +(* Other Modules in the standard library that may be of interest: + +• Logic : Classical logic and dependent equality +• Arith : Basic Peano arithmetic +• PArith : Basic positive integer arithmetic +• NArith : Basic binary natural number arithmetic +• ZArith : Basic relative integer arithmetic +• Numbers : Various approaches to natural, integer and cyclic numbers (currently + axiomatically and on top of 2^31 binary words) +• Bool : Booleans (basic functions and results) +• Lists : Monomorphic and polymorphic lists (basic functions and results), + Streams (infinite sequences defined with co-inductive types) +• Sets : Sets (classical, constructive, finite, infinite, power set, etc.) +• FSets : Specification and implementations of finite sets and finite maps + (by lists and by AVL trees) +• Reals : Axiomatization of real numbers (classical, basic functions, integer part, + fractional part, limit, derivative, Cauchy series, power series and results,...) +• Relations : Relations (definitions and basic results) +• Sorting : Sorted list (basic definitions and heapsort correctness) +• Strings : 8-bits characters and strings +• Wellfounded : Well-founded relations (basic results) + *) + +(*** User-defined data types ***) + +(* Because Coq is dependently typed, defining type aliases is no different than defining + an alias for a value. *) + +Definition my_three : nat := 3. +Definition my_nat : Type := nat. + +(* More interesting types can be defined using the Inductive vernacular. Simple enumeration + can be defined like so *) +Inductive ml := OCaml | StandardML | Coq. +Definition lang := Coq. (* Has type "ml". *) + +(* For more complicated types, you will need to specify the types of the constructors. *) + +(* Type constructors don't need to be empty. *) +Inductive my_number := plus_infinity + | nat_value : nat -> my_number. +Compute nat_value 3. (* nat_value 3 : my_number *) + + +(* Record syntax is sugar for tuple-like types. It defines named accessor functions for + the components. Record types are defined with the notation {...} *) +Record Point2d (A : Set) := mkPoint2d { x2 : A ; y2 : A }. +(* Record values are constructed with the notation {|...|} *) +Definition mypoint : Point2d nat := {| x2 := 2 ; y2 := 3 |}. +Compute x2 nat mypoint. (* 2 : nat *) +Compute mypoint.(x2 nat). (* 2 : nat *) + +(* Types can be parameterized, like in this type for "list of lists + of anything". 'a can be substituted with any type. *) +Definition list_of_lists a := list (list a). +Definition list_list_nat := list_of_lists nat. + +(* Types can also be recursive. Like in this type analogous to + built-in list of naturals. *) + +Inductive my_nat_list := EmptyList | NatList : nat -> my_nat_list -> my_nat_list. +Compute NatList 1 EmptyList. (* NatList 1 EmptyList : my_nat_list *) + +(** Matching type constructors **) + +Inductive animal := Dog : string -> animal | Cat : string -> animal. + +Definition say x := + match x with + | Dog x => (x ++ " says woof")%string + | Cat x => (x ++ " says meow")%string + end. + +Compute say (Cat "Fluffy"). (* "Fluffy says meow". *) + +(** Traversing data structures with pattern matching **) + +(* Recursive types can be traversed with pattern matching easily. + Let's see how we can traverse a data structure of the built-in list type. + Even though the built-in cons ("::") looks like an infix operator, + it's actually a type constructor and can be matched like any other. *) +Fixpoint sum_list l := + match l with + | [] => 0 + | head :: tail => head + (sum_list tail) + end. + +Compute sum_list [1; 2; 3]. (* Evaluates to 6 *) + + +(*** A Taste of Proving ***) + +(* Explaining the proof language is out of scope for this tutorial, but here is a taste to + whet your appetite. Check the resources below for more. *) + +(* A fascinating feature of dependently type based theorem provers is that the same + primitive constructs underly the proof language as the programming features. + For example, we can write and prove the proposition A and B implies A in raw Gallina *) + +Definition my_theorem : forall A B, A /\ B -> A := fun A B ab => match ab with + | (conj a b) => a + end. + +(* Or we can prove it using tactics. Tactics are a macro language to help build proof terms + in a more natural style and automate away some drudgery. *) +Theorem my_theorem2 : forall A B, A /\ B -> A. +Proof. + intros A B ab. destruct ab as [ a b ]. apply a. +Qed. + +(* We can prove easily prove simple polynomial equalities using the automated tactic ring. *) +Require Import Ring. +Require Import Arith. +Theorem simple_poly : forall (x : nat), (x + 1) * (x + 2) = x * x + 3 * x + 2. + Proof. intros. ring. Qed. + +(* Here we prove the closed form for the sum of all numbers 1 to n using induction *) + +Fixpoint sumn (n : nat) : nat := + match n with + | 0 => 0 + | (S n') => n + (sumn n') + end. + +Theorem sum_formula : forall n, 2 * (sumn n) = (n + 1) * n. +Proof. intros n. induction n. + - reflexivity. (* 0 = 0 base case *) + - simpl. ring [IHn]. (* induction step *) +Qed. +``` + +With this we have only scratched the surface of Coq. It is a massive ecosystem with many interesting and peculiar topics leading all the way up to modern research. + +## Further reading + +* [The Coq reference manual](https://coq.inria.fr/refman/) +* [Software Foundations](https://softwarefoundations.cis.upenn.edu/) +* [Certified Programming with Dependent Types](http://adam.chlipala.net/cpdt/) +* [Mathematical Components](https://math-comp.github.io/mcb/) +* [Coq'Art: The Calculus of Inductive Constructions](http://www.cse.chalmers.se/research/group/logic/TypesSS05/resources/coq/CoqArt/) +* [FRAP](http://adam.chlipala.net/frap/) diff --git a/csharp.html.markdown b/csharp.html.markdown index df6544d3..37573e01 100644 --- a/csharp.html.markdown +++ b/csharp.html.markdown @@ -14,20 +14,22 @@ filename: LearnCSharp.cs C# is an elegant and type-safe object-oriented language that enables developers to build a variety of secure and robust applications that run on the .NET Framework. -[Read more here.](http://msdn.microsoft.com/en-us/library/vstudio/z1zx9t92.aspx) +[Read more here.](https://docs.microsoft.com/dotnet/csharp/getting-started/introduction-to-the-csharp-language-and-the-net-framework) ```c# // Single-line comments start with // + /* Multi-line comments look like this */ + /// <summary> /// This is an XML documentation comment which can be used to generate external /// documentation or provide context help within an IDE /// </summary> /// <param name="firstParam">This is some parameter documentation for firstParam</param> /// <returns>Information on the returned value of a function</returns> -//public void MethodOrClassOrOtherWithParsableHelp(string firstParam) {} +public void MethodOrClassOrOtherWithParsableHelp(string firstParam) {} // Specify the namespaces this source code will be using // The namespaces below are all part of the standard .NET Framework Class Library @@ -254,7 +256,7 @@ on a new line! ""Wow!"", the masses cried"; int fooWhile = 0; while (fooWhile < 100) { - //Iterated 100 times, fooWhile 0->99 + // Iterated 100 times, fooWhile 0->99 fooWhile++; } @@ -273,10 +275,10 @@ on a new line! ""Wow!"", the masses cried"; } while (fooDoWhile < 100); - //for loop structure => for(<start_statement>; <conditional>; <step>) + // for loop structure => for(<start_statement>; <conditional>; <step>) for (int fooFor = 0; fooFor < 10; fooFor++) { - //Iterated 10 times, fooFor 0->9 + // Iterated 10 times, fooFor 0->9 } // For Each Loop @@ -287,7 +289,7 @@ on a new line! ""Wow!"", the masses cried"; // (The ToCharArray() could be removed, because a string also implements IEnumerable) foreach (char character in "Hello World".ToCharArray()) { - //Iterated over all the characters in the string + // Iterated over all the characters in the string } // Switch Case @@ -329,7 +331,7 @@ on a new line! ""Wow!"", the masses cried"; // Convert String To Integer // this will throw a FormatException on failure - int.Parse("123");//returns an integer version of "123" + int.Parse("123"); // returns an integer version of "123" // try parse will default to type default on failure // in this case: 0 @@ -373,7 +375,7 @@ on a new line! ""Wow!"", the masses cried"; Console.Read(); } // End main method - // CONSOLE ENTRY A console application must have a main method as an entry point + // CONSOLE ENTRY - A console application must have a main method as an entry point public static void Main(string[] args) { OtherInterestingFeatures(); @@ -404,7 +406,7 @@ on a new line! ""Wow!"", the masses cried"; ref int maxCount, // Pass by reference out int count) { - //the argument passed in as 'count' will hold the value of 15 outside of this function + // the argument passed in as 'count' will hold the value of 15 outside of this function count = 15; // out param must be assigned before control leaves the method } @@ -552,7 +554,7 @@ on a new line! ""Wow!"", the masses cried"; } // PARALLEL FRAMEWORK - // http://blogs.msdn.com/b/csharpfaq/archive/2010/06/01/parallel-programming-in-net-framework-4-getting-started.aspx + // https://devblogs.microsoft.com/csharpfaq/parallel-programming-in-net-framework-4-getting-started/ var words = new List<string> {"dog", "cat", "horse", "pony"}; @@ -564,11 +566,11 @@ on a new line! ""Wow!"", the masses cried"; } ); - //Running this will produce different outputs - //since each thread finishes at different times. - //Some example outputs are: - //cat dog horse pony - //dog horse pony cat + // Running this will produce different outputs + // since each thread finishes at different times. + // Some example outputs are: + // cat dog horse pony + // dog horse pony cat // DYNAMIC OBJECTS (great for working with other languages) dynamic student = new ExpandoObject(); @@ -865,7 +867,7 @@ on a new line! ""Wow!"", the masses cried"; } } - //Method to display the attribute values of this Object. + // Method to display the attribute values of this Object. public virtual string Info() { return "Gear: " + Gear + @@ -960,7 +962,7 @@ on a new line! ""Wow!"", the masses cried"; /// <summary> /// Used to connect to DB for LinqToSql example. /// EntityFramework Code First is awesome (similar to Ruby's ActiveRecord, but bidirectional) - /// http://msdn.microsoft.com/en-us/data/jj193542.aspx + /// https://docs.microsoft.com/ef/ef6/modeling/code-first/workflows/new-database /// </summary> public class BikeRepository : DbContext { @@ -1069,7 +1071,7 @@ on a new line! ""Wow!"", the masses cried"; { private static bool LogException(Exception ex) { - /* log exception somewhere */ + // log exception somewhere return false; } @@ -1117,12 +1119,12 @@ on a new line! ""Wow!"", the masses cried"; [Obsolete("Use NewMethod instead", false)] public static void ObsoleteMethod() { - /* obsolete code */ + // obsolete code } public static void NewMethod() { - /* new code */ + // new code } public static void Main() @@ -1154,9 +1156,9 @@ namespace Learning.More.CSharp } } -//New C# 7 Feature -//Install Microsoft.Net.Compilers Latest from Nuget -//Install System.ValueTuple Latest from Nuget +// New C# 7 Feature +// Install Microsoft.Net.Compilers Latest from Nuget +// Install System.ValueTuple Latest from Nuget using System; namespace Csharp7 { @@ -1310,13 +1312,11 @@ namespace Csharp7 ## Further Reading - * [DotNetPerls](http://www.dotnetperls.com) - * [C# in Depth](http://manning.com/skeet2) - * [Programming C#](http://shop.oreilly.com/product/0636920024064.do) - * [LINQ](http://shop.oreilly.com/product/9780596519254.do) - * [MSDN Library](http://msdn.microsoft.com/en-us/library/618ayhy6.aspx) - * [ASP.NET MVC Tutorials](http://www.asp.net/mvc/tutorials) - * [ASP.NET Web Matrix Tutorials](http://www.asp.net/web-pages/tutorials) - * [ASP.NET Web Forms Tutorials](http://www.asp.net/web-forms/tutorials) - * [Windows Forms Programming in C#](http://www.amazon.com/Windows-Forms-Programming-Chris-Sells/dp/0321116208) - * [C# Coding Conventions](http://msdn.microsoft.com/en-us/library/vstudio/ff926074.aspx) + * [C# language reference](https://docs.microsoft.com/dotnet/csharp/language-reference/) + * [Learn .NET](https://dotnet.microsoft.com/learn) + * [C# Coding Conventions](https://docs.microsoft.com/en-us/dotnet/csharp/programming-guide/inside-a-program/coding-conventions) + * [DotNetPerls](https://www.dotnetperls.com/) + * [C# in Depth](https://manning.com/skeet3) + * [Programming C# 5.0](http://shop.oreilly.com/product/0636920024064) + * [LINQ Pocket Reference](http://shop.oreilly.com/product/9780596519254) + * [Windows Forms Programming in C#](https://www.amazon.com/Windows-Forms-Programming-Chris-Sells/dp/0321116208) diff --git a/de-de/c++-de.html.markdown b/de-de/c++-de.html.markdown index cef7514b..87e75ad6 100644 --- a/de-de/c++-de.html.markdown +++ b/de-de/c++-de.html.markdown @@ -9,6 +9,7 @@ contributors: - ["Ankush Goyal", "http://github.com/ankushg07"] - ["Jatin Dhankhar", "https://github.com/jatindhankhar"] - ["Maximilian Sonnenburg", "https://github.com/LamdaLamdaLamda"] + - ["caminsha", "https://github.com/caminsha"] lang: de-de --- @@ -22,9 +23,9 @@ entworfen wurde um, - Objektorientierung zu unterstützen - generische Programmierung zu unterstützen -Durch seinen Syntax kann sie durchaus schwieriger und komplexer als neuere Sprachen sein. +Durch seine Syntax kann sie durchaus schwieriger und komplexer als neuere Sprachen sein. -Sie ist weit verbreitet, weil sie in Maschinen-Code kompiliert, welches direkt vom Prozessor ausgeführt +Sie ist weit verbreitet, weil sie in Maschinen-Code kompiliert, welcher direkt vom Prozessor ausgeführt werden kann und somit eine strikte Kontrolle über die Hardware bietet und gleichzeitig High-Level-Features wie generics, exceptions und Klassen enthält. @@ -36,7 +37,7 @@ weitverbreitesten Programmiersprachen. // Vergleich zu C ////////////////// -// C ist fast eine Untermenge von C++ und teilt sich grundsätzlich den +// C ist fast eine Untermenge von C++ und teilt sich grundsätzlich die // Syntax für Variablen Deklarationen, primitiven Typen und Funktionen. // Wie in C ist der Programmeinsprungpunkt eine Funktion, welche "main" genannt wird und @@ -137,7 +138,7 @@ void invalidDeclaration(int a = 1, int b) // Fehler! ///////////// -// Namespaces (Namesräume) +// Namespaces (Namensräume) ///////////// // Namespaces stellen einen getrennten Gültigkeitsbereich für Variablen, @@ -169,7 +170,7 @@ void foo() int main() { - // Fügt all Symbole aus dem namespace Second in den aktuellen Gültigkeitsbereich (scope). + // Fügt alle Symbole aus dem namespace Second in den aktuellen Gültigkeitsbereich (scope). // "foo()" wird nun nicht länger funktionieren, da es nun doppeldeutig ist, ob foo aus // dem namespace foo oder darüberliegenden aufgerufen wird. using namespace Second; @@ -283,7 +284,7 @@ string retVal = tempObjectFun(); // für Details). Wie in diesem Code: foo(bar(tempObjectFun())) -// Nehmen wir an foo und bar existieren. Das Objekt wird von "tempObjectFun" zurückgegeben, +// Nehmen wir an, foo und bar existieren. Das Objekt wird von "tempObjectFun" zurückgegeben, // wird an bar übergeben und ist zerstört bevor foo aufgerufen wird. // Zurück zu Referenzen. Die Annahme, dass die "am Ende des Ausdrucks" Regel gültig ist, @@ -335,7 +336,7 @@ ECarTypes GetPreferredCarType() return ECarTypes::Hatchback; } -// Mit C++11 existiert eine einfache Möglichkeit einem Typ dem Enum zu zuweisen. Dies +// Mit C++11 existiert eine einfache Möglichkeit einem Typ dem Enum zuzuweisen. Dies // kann durchaus sinnvoll bei der Serialisierung von Daten sein, oder bei der Konvertierung // zwischen Typen bzw. Konstanten. enum ECarTypes : uint8_t @@ -574,7 +575,7 @@ int main () // Templates in C++ werden in erster Linie dafür verwendet generisch zu programmieren. // Sie unterstützen explizite und partielle Spezialisierung und darüber hinaus können // sie für funktionale Klassen verwendet werden. -// Tatsächlich bilden templates die Turing-Vollständigkeit +// Tatsächlich bilden Templates die Turing-Vollständigkeit // (universelle Programmierbarkeit) ab. @@ -588,12 +589,12 @@ public: void insert(const T&) { ... } }; -// Während der Kompilierung generiert der Compiler Kopien für jedes template, wobei +// Während der Kompilierung generiert der Compiler Kopien für jedes Template, wobei // hierbei die Parameter substituiert werden. Somit muss bei jedem Aufruf die gesamte // Definition der Klasse zur Verfügung stehen. Aus diesem Grund wird ein Template // komplett im header definiert. -// Erzeugung einer Template-Klasse auf dem stack: +// Erzeugung einer Template-Klasse auf dem Stack: Box<int> intBox; // eine der zu erwartenden Verwendungen: @@ -612,7 +613,7 @@ boxOfBox.insert(intBox); // sind fast identisch hinsichtlich der Funktionalität. Weitere // Informationen auf: http://en.wikipedia.org/wiki/Typename -// Eine template-Funktion: +// Eine Template-Funktion: template<class T> void barkThreeTimes(const T& input) { @@ -622,7 +623,7 @@ void barkThreeTimes(const T& input) } // Hierbei ist zu beachten, dass an dieser Stelle nichts über den Typen des Parameters -// definiert wurde. Der Kompiler wird bei jedem Aufruf bzw. jeder Erzeugung den Typen +// definiert wurde. Der Compiler wird bei jedem Aufruf bzw. jeder Erzeugung den Typen // prüfen. Somit funktioniert die zuvor definierte Funktion für jeden Typ 'T', die die // const Methode 'bark' implementiert hat. @@ -637,10 +638,10 @@ void printMessage() cout << "Learn C++ in " << Y << " minutes!" << endl; } -// Des Weiteren können templates aus Effizienzgründen genauer spezifiziert werden. -// Selbstverständlich sind reale-Problemen, welche genauer spezifiziert werden nicht +// Des Weiteren können Templates aus Effizienzgründen genauer spezifiziert werden. +// Selbstverständlich sind reale Probleme, welche genauer spezifiziert werden, nicht // derart trivial. Auch wenn alle Parameter explizit definiert wurden, muss die -// Funktion oder Klasse als template deklariert werden. +// Funktion oder Klasse als Template deklariert werden. template<> void printMessage<10>() { @@ -818,9 +819,9 @@ void doSomethingWithAFile(const std::string& filename) // Container ///////////////////// -// Die Container der Standard template Bibliothek beinhaltet einige vordefinierter templates. +// Die Container der Standard template Bibliothek beinhaltet einige vordefinierte Templates. // Diese verwalten die Speicherbereiche für die eigenen Elemente und stellen Member-Funktionen -// für den Zugriff und die Maniplulation bereit. +// für den Zugriff und die Manipulation bereit. // Beispielhafte Container: @@ -876,7 +877,7 @@ for(it=ST.begin();it<ST.end();it++) // 10 // 30 -// Zum leeren des gesamten Container wird die Methode +// Zum leeren des gesamten Containers wird die Methode // Container._name.clear() verwendet. ST.clear(); cout << ST.size(); // Ausgabe der Set-Größe @@ -948,11 +949,11 @@ fooMap.find(Foo(1)); // Wahr // Lambda Ausdrücke (C++11 und höher) /////////////////////////////////////// -// Lambdas sind eine gängige Methodik um anonyme Funktionen an dem +// Lambdas sind eine gängige Methodik, um anonyme Funktionen an dem // Ort der Verwendung zu definieren. Darüber hinaus auch bei der // Verwendung von Funktionen als Argument einer Funktion. -// Nehmen wir an es soll ein Vektor von "pairs" (Paaren) mithilfe +// Nehmen wir an, es soll ein Vektor von "pairs" (Paaren) mithilfe // des zweiten Werts des "pairs" sortiert werden. vector<pair<int, int> > tester; @@ -966,7 +967,7 @@ sort(tester.begin(), tester.end(), [](const pair<int, int>& lhs, const pair<int, return lhs.second < rhs.second; }); -// Beachte den Syntax von Lambda-Ausdrücken. +// Beachte die Syntax von Lambda-Ausdrücken. // Die [] im Lambda Ausdruck werden für die Variablen verwendet. // Diese so genannte "capture list" definiert, was außerhalb des Lambdas, // innerhalb der Funktion verfügbar sein soll und in welcher Form. @@ -1025,7 +1026,7 @@ for(auto elem: arr) // Einige Aspekte von C++ sind für Neueinsteiger häufig überraschend (aber auch für // C++ Veteranen). // Der nachfolgende Abschnitt ist leider nicht vollständig: -// C++ ist eine der Sprachen, bei der es ein leichtes ist sich selbst ins Bein zu schießen. +// C++ ist eine der Sprachen, bei der es ein Leichtes ist, sich selbst ins Bein zu schießen. // Private-Methoden können überschrieben werden class Foo @@ -1074,10 +1075,10 @@ f1 = f2; #include<tuple> -// Konzeptionell sind Tuple´s alten Datenstrukturen sehr ähnlich, allerdings haben diese keine +// Konzeptionell sind Tupel alten Datenstrukturen sehr ähnlich, allerdings haben diese keine // bezeichneten Daten-Member, sondern werden durch die Reihenfolge angesprochen. -// Erstellen des Tuples und das Einfügen eines Werts. +// Erstellen des Tupels und das Einfügen eines Werts. auto first = make_tuple(10, 'A'); const int maxN = 1e9; const int maxL = 15; @@ -1102,7 +1103,7 @@ tuple<int, char, double> third(11, 'A', 3.14141); cout << tuple_size<decltype(third)>::value << "\n"; // prints: 3 -// tuple_cat fügt die Elemente eines Tuples aneinander (in der selben Reihenfolge). +// tuple_cat fügt die Elemente eines Tupels aneinander (in der selben Reihenfolge). auto concatenated_tuple = tuple_cat(first, second, third); // concatenated_tuple wird zu = (10, 'A', 1e9, 15, 11, 'A', 3.14141) diff --git a/haxe.html.markdown b/haxe.html.markdown index a31728e1..e086dd7a 100644 --- a/haxe.html.markdown +++ b/haxe.html.markdown @@ -6,8 +6,8 @@ contributors: - ["Dan Korostelev", "https://github.com/nadako/"] --- -Haxe is a web-oriented language that provides platform support for C++, C#, -Swf/ActionScript, Javascript, Java, PHP, Python, Lua, HashLink, and Neko byte code +[Haxe](https://haxe.org/) is a general-purpose language that provides platform support for C++, C#, +Swf/ActionScript, JavaScript, Java, PHP, Python, Lua, HashLink, and Neko bytecode (the latter two being also written by the Haxe author). Note that this guide is for Haxe version 3. Some of the guide may be applicable to older versions, but it is recommended to use other references. @@ -189,7 +189,7 @@ class LearnHaxe3 { trace(m.get('bar') + " is the value for m.get('bar')"); trace(m['bar'] + " is the value for m['bar']"); - var m2 = ['foo' => 4, 'baz' => 6]; // Alternative map syntax + var m2 = ['foo' => 4, 'baz' => 6]; // Alternative map syntax trace(m2 + " is the value for m2"); // Remember, you can use type inference. The Haxe compiler will @@ -234,10 +234,9 @@ class LearnHaxe3 { ^ Bitwise exclusive OR | Bitwise inclusive OR */ - - // increments + var i = 0; - trace("Increments and decrements"); + trace("Pre-/Post- Increments and Decrements"); trace(i++); // i = 1. Post-Increment trace(++i); // i = 2. Pre-Increment trace(i--); // i = 1. Post-Decrement @@ -287,7 +286,7 @@ class LearnHaxe3 { } // do-while loop - var l = 0; + var l = 0; do { trace("do statement always runs at least once"); } while (l > 0); @@ -338,7 +337,7 @@ class LearnHaxe3 { */ var my_dog_name = "fido"; var favorite_thing = ""; - switch(my_dog_name) { + switch (my_dog_name) { case "fido" : favorite_thing = "bone"; case "rex" : favorite_thing = "shoe"; case "spot" : favorite_thing = "tennis ball"; @@ -366,7 +365,7 @@ class LearnHaxe3 { trace("k equals ", k); // outputs 10 - var other_favorite_thing = switch(my_dog_name) { + var other_favorite_thing = switch (my_dog_name) { case "fido" : "teddy"; case "rex" : "stick"; case "spot" : "football"; @@ -559,7 +558,7 @@ class SimpleEnumTest { // You can specify the "full" name, var e_explicit:SimpleEnum = SimpleEnum.Foo; var e = Foo; // but inference will work as well. - switch(e) { + switch (e) { case Foo: trace("e was Foo"); case Bar: trace("e was Bar"); case Baz: trace("e was Baz"); // comment this line to throw an error. @@ -572,7 +571,7 @@ class SimpleEnumTest { You can also specify a default for enum switches as well: */ - switch(e) { + switch (e) { case Foo: trace("e was Foo again"); default : trace("default works here too"); } @@ -595,21 +594,21 @@ class ComplexEnumTest { var e1:ComplexEnum = IntEnum(4); // specifying the enum parameter // Now we can switch on the enum, as well as extract any parameters // it might have had. - switch(e1) { + switch (e1) { case IntEnum(x) : trace('$x was the parameter passed to e1'); default: trace("Shouldn't be printed"); } // another parameter here that is itself an enum... an enum enum? var e2 = SimpleEnumEnum(Foo); - switch(e2){ + switch (e2){ case SimpleEnumEnum(s): trace('$s was the parameter passed to e2'); default: trace("Shouldn't be printed"); } // enums all the way down var e3 = ComplexEnumEnum(ComplexEnumEnum(MultiEnum(4, 'hi', 4.3))); - switch(e3) { + switch (e3) { // You can look for certain nested enums by specifying them // explicitly: case ComplexEnumEnum(ComplexEnumEnum(MultiEnum(i,j,k))) : { @@ -668,7 +667,7 @@ class TypedefsAndStructuralTypes { That would give us a single "Surface" type to work with across all of those platforms. - */ + */ } } @@ -700,8 +699,7 @@ class UsingExample { instance, and the compiler still generates code equivalent to a static method. */ - } - + } } ``` diff --git a/javascript.html.markdown b/javascript.html.markdown index c466c09b..ce9772ca 100644 --- a/javascript.html.markdown +++ b/javascript.html.markdown @@ -586,6 +586,48 @@ if (Object.create === undefined){ // don't overwrite it if it exists return new Constructor(); }; } + +// ES6 Additions + +// The "let" keyword allows you to define variables in a lexical scope, +// as opposed to a block scope like the var keyword does. +let name = "Billy"; + +// Variables defined with let can be reassigned new values. +name = "William"; + +// The "const" keyword allows you to define a variable in a lexical scope +// like with let, but you cannot reassign the value once one has been assigned. + +const pi = 3.14; + +pi = 4.13; // You cannot do this. + +// There is a new syntax for functions in ES6 known as "lambda syntax". +// This allows functions to be defined in a lexical scope like with variables +// defined by const and let. + +const isEven = (number) => { + return number % 2 === 0; +}; + +isEven(7); // false + +// The "equivalent" of this function in the traditional syntax would look like this: + +function isEven(number) { + return number % 2 === 0; +}; + +// I put the word "equivalent" in double quotes because a function defined +// using the lambda syntax cannnot be called before the definition. +// The following is an example of invalid usage: + +add(1, 8); + +const add = (firstNumber, secondNumber) => { + return firstNumber + secondNumber; +}; ``` ## Further Reading diff --git a/perl6.html.markdown b/perl6.html.markdown deleted file mode 100644 index c7fde218..00000000 --- a/perl6.html.markdown +++ /dev/null @@ -1,1976 +0,0 @@ ---- -category: language -language: perl6 -filename: learnperl6.p6 -contributors: - - ["vendethiel", "http://github.com/vendethiel"] - - ["Samantha McVey", "https://cry.nu"] ---- - -Perl 6 is a highly capable, feature-rich programming language made for at -least the next hundred years. - -The primary Perl 6 compiler is called [Rakudo](http://rakudo.org), which runs on -the JVM and [the MoarVM](http://moarvm.com). - -Meta-note: double pound signs (`##`) are used to indicate paragraphs, -while single pound signs (`#`) indicate notes. - -`#=>` represents the output of a command. - -```perl6 -# Single line comments start with a pound sign. - -#`( Multiline comments use #` and a quoting construct. - (), [], {}, 「」, etc, will work. -) - -# Use the same syntax for multiline comments to embed comments. -for #`(each element in) @array { - put #`(or print element) $_ #`(with newline); -} -``` - -## Variables - -```perl6 -## In Perl 6, you declare a lexical variable using the `my` keyword: -my $variable; -## Perl 6 has 3 basic types of variables: scalars, arrays, and hashes. -``` - -### Scalars - -```perl6 -# Scalars represent a single value. They start with the `$` sigil: -my $str = 'String'; - -# Double quotes allow for interpolation (which we'll see later): -my $str2 = "String"; - -## Variable names can contain but not end with simple quotes and dashes, -## and can contain (and end with) underscores: -my $person's-belongings = 'towel'; # this works! - -my $bool = True; # `True` and `False` are Perl 6's boolean values. -my $inverse = !$bool; # Invert a bool with the prefix `!` operator. -my $forced-bool = so $str; # And you can use the prefix `so` operator -$forced-bool = ?$str; # to turn its operand into a Bool. Or use `?`. -``` - -### Arrays and Lists - -```perl6 -## Arrays represent multiple values. An array variable starts with the `@` -## sigil. Unlike lists, from which arrays inherit, arrays are mutable. - -my @array = 'a', 'b', 'c'; -# equivalent to: -my @letters = <a b c>; # array of words, delimited by space. - # Similar to perl5's qw, or Ruby's %w. -@array = 1, 2, 3; - -say @array[2]; # Array indices start at 0. Here the third element - # is being accessed. - -say "Interpolate an array using []: @array[]"; -#=> Interpolate an array using []: 1 2 3 - -@array[0] = -1; # Assigning a new value to an array index -@array[0, 1] = 5, 6; # Assigning multiple values - -my @keys = 0, 2; -@array[@keys] = @letters; # Assignment using an array containing index values -say @array; #=> a 6 b -``` - -### Hashes, or key-value Pairs. - -```perl6 -## Hashes are pairs of keys and values. You can construct a `Pair` object -## using the syntax `Key => Value`. Hash tables are very fast for lookup, -## and are stored unordered. Keep in mind that keys get "flattened" in hash -## context, and any duplicated keys are deduplicated. -my %hash = 'a' => 1, 'b' => 2; - -%hash = a => 1, # keys get auto-quoted when => (fat comma) is used. - b => 2, # Trailing commas are okay. -; - -## Even though hashes are internally stored differently than arrays, -## Perl 6 allows you to easily create a hash from an even numbered array: -%hash = <key1 value1 key2 value2>; # Or: -%hash = "key1", "value1", "key2", "value2"; - -%hash = key1 => 'value1', key2 => 'value2'; # same result as above - -## You can also use the "colon pair" syntax. This syntax is especially -## handy for named parameters that you'll see later. -%hash = :w(1), # equivalent to `w => 1` - :truey, # equivalent to `:truey(True)` or `truey => True` - :!falsey, # equivalent to `:falsey(False)` or `falsey => False` -; -## The :truey and :!falsey constructs are known as the -## `True` and `False` shortcuts respectively. - -say %hash{'key1'}; # You can use {} to get the value from a key. -say %hash<key2>; # If it's a string without spaces, you can actually use - # <> (quote-words operator). `{key1}` doesn't work, - # as Perl6 doesn't have barewords. -``` - -## Subs - -```perl6 -## Subroutines, or functions as most other languages call them, are -## created with the `sub` keyword. -sub say-hello { say "Hello, world" } - -## You can provide (typed) arguments. If specified, the type will be checked -## at compile-time if possible, otherwise at runtime. -sub say-hello-to( Str $name ) { - say "Hello, $name !"; -} - -## A sub returns the last value of the block. Similarly, the semicolon in -## the last can be omitted. -sub return-value { 5 } -say return-value; # prints 5 - -sub return-empty { } -say return-empty; # prints Nil - -## Some control flow structures produce a value, like `if`: -sub return-if { - if True { "Truthy" } -} -say return-if; # prints Truthy - -## Some don't, like `for`: -sub return-for { - for 1, 2, 3 { 'Hi' } -} -say return-for; # prints Nil - -## Positional arguments are required by default. To make them optional, use -## the `?` after the parameters' names. -sub with-optional( $arg? ) { - # This sub returns `(Any)` (Perl's null-like value) if - # no argument is passed. Otherwise, it returns its argument. - $arg; -} -with-optional; # returns Any -with-optional(); # returns Any -with-optional(1); # returns 1 - -## You can also give them a default value when they're not passed. -## Required parameters must come before optional ones. -sub greeting( $name, $type = "Hello" ) { - say "$type, $name!"; -} - -greeting("Althea"); #=> Hello, Althea! -greeting("Arthur", "Good morning"); #=> Good morning, Arthur! - -## You can also, by using a syntax akin to the one of hashes -## (yay unified syntax !), pass *named* arguments to a `sub`. They're -## optional, and will default to "Any". -sub with-named( $normal-arg, :$named ) { - say $normal-arg + $named; -} -with-named(1, named => 6); #=> 7 - -## There's one gotcha to be aware of, here: If you quote your key, Perl 6 -## won't be able to see it at compile time, and you'll have a single `Pair` -## object as a positional parameter, which means -## `with-named(1, 'named' => 6);` fails. - -with-named(2, :named(5)); #=> 7 - -## To make a named argument mandatory, you can append `!` to the parameter, -## which is the inverse of `?`: -sub with-mandatory-named( :$str! ) { - say "$str!"; -} -with-mandatory-named(str => "My String"); #=> My String! -with-mandatory-named; # runtime error:"Required named parameter not passed" -with-mandatory-named(3);# runtime error:"Too many positional parameters passed" - -## If a sub takes a named boolean argument... -sub takes-a-bool( $name, :$bool ) { - say "$name takes $bool"; -} -## ... you can use the same "short boolean" hash syntax: -takes-a-bool('config', :bool); #=> config takes True -takes-a-bool('config', :!bool); #=> config takes False - -## You can also provide your named arguments with default values: -sub named-def( :$def = 5 ) { - say $def; -} -named-def; #=> 5 -named-def(def => 15); #=> 15 - -## Since you can omit parenthesis to call a function with no arguments, -## you need `&` in the name to store `say-hello` in a variable. This means -## `&say-hello` is a code object and not a subroutine call. -my &s = &say-hello; -my &other-s = sub { say "Anonymous function!" } - -## A sub can have a "slurpy" parameter, or "doesn't-matter-how-many". For -## this, you must use `*@` (slurpy) which will "take everything else". You can -## have as many parameters *before* a slurpy one, but not *after*. -sub as-many($head, *@rest) { - say @rest.join(' / ') ~ " !"; -} -say as-many('Happy', 'Happy', 'Birthday');#=> Happy / Birthday ! - # Note that the splat (the *) did not - # consume the parameter before it. - -## You can call a function with an array using the "argument list flattening" -## operator `|` (it's not actually the only role of this operator, -## but it's one of them). -sub concat3($a, $b, $c) { - say "$a, $b, $c"; -} -concat3(|@array); #=> a, b, c - # `@array` got "flattened" as a part of the argument list -``` - -## Containers - -```perl6 -## In Perl 6, values are actually stored in "containers". The assignment -## operator asks the container on the left to store the value on its right. -## When passed around, containers are marked as immutable which means that, -## in a function, you'll get an error if you try to mutate one of your -## arguments. If you really need to, you can ask for a mutable container by -## using the `is rw` trait: -sub mutate( $n is rw ) { - $n++; # postfix ++ operator increments its argument but returns its old value -} - -my $m = 42; -mutate $m; # the value is incremented but the old value is returned - #=> 42 -say $m; #=> 43 - -## This works because we are passing the container $m to the `mutate` sub. -## If we try to just pass a number instead of passing a variable it won't work -## because there is no container being passed and integers are immutable by -## themselves: - -mutate 42; # Parameter '$n' expected a writable container, but got Int value - -## Similar error would be obtained, if a bound variable is passed to -## to the subroutine: - -my $v := 50; # binding 50 to the variable $v -mutate $v; # Parameter '$n' expected a writable container, but got Int value - -## If what you want is a copy instead, use the `is copy` trait which will -## cause the argument to be copied and allow you to modify the argument -## inside the routine. - -## A sub itself returns a container, which means it can be marked as rw: -my $x = 42; -sub x-store() is rw { $x } -x-store() = 52; # in this case, the parentheses are mandatory - # (else Perl 6 thinks `x-store` is an identifier) -say $x; #=> 52 -``` - -## Control Flow Structures - -### Conditionals - -```perl6 -## - `if` -## Before talking about `if`, we need to know which values are "Truthy" -## (represent True), and which are "Falsey" (represent False). Only these -## values are Falsey: 0, (), {}, "", Nil, A type (like `Str` or `Int`) and -## of course False itself. Any other value is Truthy. -if True { - say "It's true!"; -} - -unless False { - say "It's not false!"; -} - -## As you can see, you don't need parentheses around conditions. However, you -## do need the curly braces around the "body" block. For example, -## `if (true) say;` doesn't work. - -## You can also use their statement modifier (postfix) versions: -say "Quite truthy" if True; #=> Quite truthy -say "Quite falsey" unless False; #=> Quite falsey - -## - Ternary operator, "x ?? y !! z" -## This returns $value-if-true if the condition is true and $value-if-false -## if it is false. -## my $result = condition ?? $value-if-true !! $value-if-false; - -my $age = 30; -say $age > 18 ?? "You are an adult" !! "You are under 18"; -#=> You are an adult -``` - -### given/when, or Perl 6's switch construct - -```perl6 -## `given...when` looks like other languages' `switch`, but is much more -## powerful thanks to smart matching and Perl 6's "topic variable", $_. -## -## The topic variable $_ contains the default argument of a block, a loop's -## current iteration (unless explicitly named), etc. -## -## `given` simply puts its argument into `$_` (like a block would do), -## and `when` compares it using the "smart matching" (`~~`) operator. -## -## Since other Perl 6 constructs use this variable (as said before, like `for`, -## blocks, etc), this means the powerful `when` is not only applicable along -## with a `given`, but instead anywhere a `$_` exists. - -given "foo bar" { - say $_; #=> foo bar - when /foo/ { # Don't worry about smart matching yet. Just know - say "Yay !"; # `when` uses it. This is equivalent to `if $_ ~~ /foo/`. - - } - when $_.chars > 50 { # smart matching anything with True is True, - # i.e. (`$a ~~ True`) - # so you can also put "normal" conditionals. - # This `when` is equivalent to this `if`: - # `if $_ ~~ ($_.chars > 50) {...}` - # which means: `if $_.chars > 50 {...}` - say "Quite a long string !"; - } - default { # same as `when *` (using the Whatever Star) - say "Something else" - } -} -``` - -### Looping constructs - -```perl6 -## - `loop` is an infinite loop if you don't pass it arguments, but can also -## be a C-style `for` loop: -loop { - say "This is an infinite loop !"; - last; # last breaks out of the loop, like - # the `break` keyword in other languages -} - -loop (my $i = 0; $i < 5; $i++) { - next if $i == 3; # `next` skips to the next iteration, like `continue` - # in other languages. Note that you can also use postfix - # conditionals, loops, etc. - say "This is a C-style for loop!"; -} - -## - `for` - Iterating through an array - -my @array = 1, 2, 6, 7, 3; - -## Accessing the array's elements with the topic variable $_. -for @array { - say "I've got $_ !"; -} - -## Accessing the array's elements with a "pointy block", `->`. -## Here each element is read-only. -for @array -> $variable { - say "I've got $variable !"; -} - -## Accessing the array's elements with a "doubly pointy block", `<->`. -## Here each element is read-write so mutating `$variable` mutates -## that element in the array. -for @array <-> $variable { - say "I've got $variable !"; -} - -## As we saw with given, a for loop's default "current iteration" variable -## is `$_`. That means you can use `when` in a `for`loop just like you were -## able to in a `given`. -for @array { - say "I've got $_"; - - .say; # This is also allowed. A dot call with no "topic" (receiver) - # is sent to `$_` by default - $_.say; # This is equivalent to the above statement. -} - -for @array { - # You can... - next if $_ == 3; # Skip to the next iteration (`continue` in C-like lang.) - redo if $_ == 4; # Re-do iteration, keeping the same topic variable (`$_`) - last if $_ == 5; # Or break out of loop (like `break` in C-like lang.) -} - -## The "pointy block" syntax isn't specific to the `for` loop. It's just a way -## to express a block in Perl 6. -sub long-computation { "Finding factors of large primes" } -if long-computation() -> $result { - say "The result is $result."; -} -``` - -## Operators - -```perl6 -## Since Perl languages are very much operator-based languages, Perl 6 -## operators are actually just funny-looking subroutines, in syntactic -## categories, like infix:<+> (addition) or prefix:<!> (bool not). - -## The categories are: -## - "prefix": before (like `!` in `!True`). -## - "postfix": after (like `++` in `$a++`). -## - "infix": in between (like `*` in `4 * 3`). -## - "circumfix": around (like `[`-`]` in `[1, 2]`). -## - "post-circumfix": around, after another term (like `{`-`}` in -## `%hash{'key'}`) - -## The associativity and precedence list are explained below. - -## Alright, you're set to go! - -## Equality Checking -##------------------ - -## - `==` is numeric comparison -3 == 4; #=> False -3 != 4; #=> True - -## - `eq` is string comparison -'a' eq 'b'; #=> False -'a' ne 'b'; #=> True, not equal -'a' !eq 'b'; #=> True, same as above - -## - `eqv` is canonical equivalence (or "deep equality") -(1, 2) eqv (1, 3); #=> False -(1, 2) eqv (1, 2); #=> True -Int === Int #=> True - -## - `~~` is the smart match operator -## Aliases the left hand side to $_ and then evaluates the right hand side. -## Here are some common comparison semantics: - -## String or numeric equality -'Foo' ~~ 'Foo'; # True if strings are equal. -12.5 ~~ 12.50; # True if numbers are equal. - -## Regex - For matching a regular expression against the left side. -## Returns a `Match` object, which evaluates as True if regexp matches. - -my $obj = 'abc' ~~ /a/; -say $obj; #=> ｢a｣ -say $obj.WHAT; #=> (Match) - -## Hashes -'key' ~~ %hash; # True if key exists in hash. - -## Type - Checks if left side "is of type" (can check superclasses and -## roles). -say 1 ~~ Int; #=> True - -## Smart-matching against a boolean always returns that boolean -## (and will warn). -say 1 ~~ True; #=> True -say False ~~ True; #=> True - -## General syntax is `$arg ~~ &bool-returning-function;`. For a complete list -## of combinations, use this table: -## http://perlcabal.org/syn/S03.html#Smart_matching - -## Of course, you also use `<`, `<=`, `>`, `>=` for numeric comparison. -## Their string equivalent are also available: `lt`, `le`, `gt`, `ge`. -3 > 4; # False -3 >= 4; # False -3 < 4; # True -3 <= 4; # True -'a' gt 'b'; # False -'a' ge 'b'; # False -'a' lt 'b'; # True -'a' le 'b'; # True - - -## Range constructor -##------------------ -3 .. 7; # 3 to 7, both included. -3 ..^ 7; # 3 to 7, exclude right endpoint. -3 ^.. 7; # 3 to 7, exclude left endpoint. -3 ^..^ 7; # 3 to 7, exclude both endpoints. - # 3 ^.. 7 almost like 4 .. 7 when we only consider integers. - # But when we consider decimals : -3.5 ~~ 4 .. 7; # False -3.5 ~~ 3 ^.. 7; # True, This Range also contains decimals greater than 3. - # We describe it like this in some math books: 3.5 ∈ (3,7] - # If you don’t want to understand the concept of interval - # for the time being. At least we should know： -3 ^.. 7 ~~ 4 .. 7; # False - - -## This also works as a shortcut for `0..^N`: -^10; # means 0..^10 - -## This also allows us to demonstrate that Perl 6 has lazy/infinite arrays, -## using the Whatever Star: -my @array = 1..*; # 1 to Infinite! Equivalent to `1..Inf`. -say @array[^10]; # You can pass ranges as subscripts and it'll return - # an array of results. This will print - # "1 2 3 4 5 6 7 8 9 10" (and not run out of memory!) - -## Note: when reading an infinite list, Perl 6 will "reify" the elements -## it needs, then keep them in memory. They won't be calculated more than once. -## It also will never calculate more elements that are needed. - -## An array subscript can also be a closure. It'll be called with the length -## as the argument: -say join(' ', @array[15..*]); #=> 15 16 17 18 19 -## which is equivalent to: -say join(' ', @array[-> $n { 15..$n }]); - -## Note: if you try to do either of those with an infinite array, -## you'll trigger an infinite loop (your program won't finish). - -## You can use that in most places you'd expect, even when assigning to -## an array: -my @numbers = ^20; - -## Here the numbers increase by 6, like an arithmetic sequence; more on the -## sequence (`...`) operator later. -my @seq = 3, 9 ... * > 95; # 3 9 15 21 27 [...] 81 87 93 99; -@numbers[5..*] = 3, 9 ... *; # even though the sequence is infinite, - # only the 15 needed values will be calculated. -say @numbers; #=> 0 1 2 3 4 3 9 15 21 [...] 81 87 - # (only 20 values) - -## and (&&), or (||) -##------------------ -3 && 4; # 4, which is Truthy. Calls `.Bool` on both 3 and 4 and gets `True` - # so it returns 4 since both are `True`. -3 && 0; # 0 -0 && 4; # 0 - -0 || False; # False. Calls `.Bool` on `0` and `False` which are both `False` - # so it retusns `False` since both are `False`. - -## Short-circuit (and tight) versions of the above -## Return the first argument that evaluates to False, or the last argument. - -my ( $a, $b, $c ) = 1, 0, 2; -$a && $b && $c; # Returns 0, the first False value - -## || Returns the first argument that evaluates to True -$b || $a; # 1 - -## And because you're going to want them, you also have compound assignment -## operators: -$a *= 2; # multiply and assignment. Equivalent to $a = $a * 2; -$b %%= 5; # divisible by and assignment. Equivalent to $b = $b %% 2; -$c div= 3; # return divisor and assignment. Equivalent to $c = $c div 3; -$d mod= 4; # return remainder and assignment. Equivalent to $d = $d mod 4; -@array .= sort; # calls the `sort` method and assigns the result back -``` - -## More on subs! - -```perl6 -## As we said before, Perl 6 has *really* powerful subs. We're going -## to see a few more key concepts that make them better than in any -## other language :-). -``` - -### Unpacking! - -```perl6 -## Unpacking is the ability to "extract" arrays and keys -## (AKA "destructuring"). It'll work in `my`s and in parameter lists. -my ($f, $g) = 1, 2; -say $f; #=> 1 -my ($, $, $h) = 1, 2, 3; # keep the non-interesting values anonymous (`$`) -say $h; #=> 3 - -my ($head, *@tail) = 1, 2, 3; # Yes, it's the same as with "slurpy subs" -my (*@small) = 1; - -sub unpack_array( @array [$fst, $snd] ) { - say "My first is $fst, my second is $snd! All in all, I'm @array[]."; - # (^ remember the `[]` to interpolate the array) -} -unpack_array(@tail); #=> My first is 2, my second is 3! All in all, I'm 2 3. - - -## If you're not using the array itself, you can also keep it anonymous, -## much like a scalar: -sub first-of-array( @ [$fst] ) { $fst } -first-of-array(@small); #=> 1 -first-of-array(@tail); # Error: "Too many positional parameters passed" - # (which means the array is too big). - -## You can also use a slurp... -sub slurp-in-array(@ [$fst, *@rest]) { # You could keep `*@rest` anonymous - say $fst + @rest.elems; # `.elems` returns a list's length. - # Here, `@rest` is `(3,)`, since `$fst` - # holds the `2`. -} -slurp-in-array(@tail); #=> 3 - -## You could even extract on a slurpy (but it's pretty useless ;-).) -sub fst(*@ [$fst]) { # or simply: `sub fst($fst) { ... }` - say $fst; -} -fst(1); #=> 1 -fst(1, 2); # errors with "Too many positional parameters passed" - -## You can also destructure hashes (and classes, which you'll learn about -## later). The syntax is basically the same as -## `%hash-name (:key($variable-to-store-value-in))`. -## The hash can stay anonymous if you only need the values you extracted. -sub key-of( % (:value($val), :qua($qua)) ) { - say "Got val $val, $qua times."; -} - -## Then call it with a hash. You need to keep the curly braces for it to be a -## hash or use `%()` instead to indicate a hash is being passed. -key-of({value => 'foo', qua => 1}); #=> Got val foo, 1 times. -key-of(%(value => 'foo', qua => 1)); #=> Got val foo, 1 times. -#key-of(%hash); # the same (for an equivalent `%hash`) - -## The last expression of a sub is returned automatically (though you may -## indicate explicitly by using the `return` keyword, of course): -sub next-index( $n ) { - $n + 1; -} -my $new-n = next-index(3); # $new-n is now 4 - -## This is true for everything, except for the looping constructs (due to -## performance reasons): there's no reason to build a list if we're just going to -## discard all the results. If you still want to build one, you can use the -## `do` statement prefix or the `gather` prefix, which we'll see later: - -sub list-of( $n ) { - do for ^$n { # note the range-to prefix operator `^` (`0..^N`) - $_ # current loop iteration known as the "topic" variable - } -} -my @list3 = list-of(3); #=> (0, 1, 2) -``` - -### lambdas (or anonymous subroutines) - -```perl6 -## You can create a lambda with `-> {}` ("pointy block") , -## `{}` ("block") or `sub {}`. - -my &lambda1 = -> $argument { - "The argument passed to this lambda is $argument" -} - -my &lambda2 = { - "The argument passed to this lambda is $_" -} - -my &lambda3 = sub ($argument) { - "The argument passed to this lambda is $argument" -} - -## `-> {}` and `{}` are pretty much the same thing, except that the former can -## take arguments, and that the latter can be mistaken as a hash by the parser. - -## We can, for example, add 3 to each value of an array using the -## `map` function with a lambda: -my @arrayplus3 = map({ $_ + 3 }, @array); # $_ is the implicit argument - -## A sub (`sub {}`) has different semantics than a block (`{}` or `-> {}`): -## A block doesn't have a "function context" (though it can have arguments), -## which means that if you return from it, you're going to return from the -## parent function. Compare: -sub is-in( @array, $elem ) { - # this will `return` out of the `is-in` sub once the condition evaluated - ## to True, the loop won't be run anymore. - map({ return True if $_ == $elem }, @array); -} -## with: -sub truthy-array( @array ) { - # this will produce an array of `True` and `False`: - # (you can also say `anon sub` for "anonymous subroutine") - map(sub ($i) { if $i { return True } else { return False } }, @array); - # ^ the `return` only returns from the anonymous `sub` -} - -## The `anon` declarator can be used to create an anonymous sub from a -## regular subroutine. The regular sub knows its name but its symbol is -## prevented from getting installed in the lexical scope, the method table -## and everywhere else. - -my $anon-sum = anon sub summation(*@a) { [+] *@a } -say $anon-sum.name; #=> summation -say $anon-sum(2, 3, 5); #=> 10 -#say summation; #=> Error: Undeclared routine: ... - -## You can also use the "whatever star" to create an anonymous subroutine. -## (it'll stop at the furthest operator in the current expression) -my @arrayplus3 = map(*+3, @array); # `*+3` is the same as `{ $_ + 3 }` -my @arrayplus3 = map(*+*+3, @array); # Same as `-> $a, $b { $a + $b + 3 }` - # also `sub ($a, $b) { $a + $b + 3 }` -say (*/2)(4); #=> 2 - # Immediately execute the function Whatever created. -say ((*+3)/5)(5); #=> 1.6 - # It works even in parens! - -## But if you need to have more than one argument (`$_`) in a block (without -## wanting to resort to `-> {}`), you can also use the implicit argument -## syntax, `$^`: -map({ $^a + $^b + 3 }, @array); -# which is equivalent to the following which uses a `sub`: -map(sub ($a, $b) { $a + $b + 3 }, @array); - -## The parameters `$^a`, `$^b`, etc. are known as placeholder parameters or -## self-declared positional parameters. They're sorted lexicographically so -## `{ $^b / $^a }` is equivalent `-> $a, $b { $b / $a }`. -``` - -### About types... - -```perl6 -## Perl 6 is gradually typed. This means you can specify the type of your -## variables/arguments/return types, or you can omit the type annotations in -## in which case they'll default to `Any`. Obviously you get access to a few -## base types, like `Int` and `Str`. The constructs for declaring types are -## "subset", "class", "role", etc. which you'll see later. - -## For now, let us examine "subset" which is a "sub-type" with additional -## checks. For example, "a very big integer is an Int that's greater than 500". -## You can specify the type you're subtyping (by default, `Any`), and add -## additional checks with the `where` clause: -subset VeryBigInteger of Int where * > 500; -## Or the set of the whole numbers: -subset WholeNumber of Int where * >= 0; -``` - -### Multiple Dispatch - -```perl6 -## Perl 6 can decide which variant of a `sub` to call based on the type of the -## arguments, or on arbitrary preconditions, like with a type or `where`: - -## with types: -multi sub sayit( Int $n ) { # note the `multi` keyword here - say "Number: $n"; -} -multi sayit( Str $s ) { # a multi is a `sub` by default - say "String: $s"; -} -sayit("foo"); #=> "String: foo" -sayit(25); #=> "Number: 25" -sayit(True); # fails at *compile time* with "calling 'sayit' will never - # work with arguments of types ..." - -## with arbitrary preconditions (remember subsets?): -multi is-big(Int $n where * > 50) { "Yes!" } # using a closure -multi is-big(Int $n where {$_ > 50}) { "Yes!" } # similar to above -multi is-big(Int $ where 10..50) { "Quite." } # Using smart-matching - # (could use a regexp, etc) -multi is-big(Int $) { "No" } - -subset Even of Int where * %% 2; -multi odd-or-even(Even) { "Even" } # The main case using the type. - # We don't name the argument. -multi odd-or-even($) { "Odd" } # "everthing else" hence the $ variable - -## You can even dispatch based on the presence of positional and -## named arguments: -multi with-or-without-you($with) { - say "I wish I could but I can't"; -} -multi with-or-without-you(:$with) { - say "I can live! Actually, I can't."; -} -multi with-or-without-you { - say "Definitely can't live."; -} - -## This is very, very useful for many purposes, like `MAIN` subs (covered -## later), and even the language itself uses it in several places. -## -## - `is`, for example, is actually a `multi sub` named `trait_mod:<is>`, -## and it works off that. -## - `is rw`, is simply a dispatch to a function with this signature: -## sub trait_mod:<is>(Routine $r, :$rw!) {} -## -## (commented out because running this would be a terrible idea!) -``` - -## Scoping - -```perl6 -## In Perl 6, unlike many scripting languages, (such as Python, Ruby, PHP), -## you must declare your variables before using them. The `my` declarator -## you have learned uses "lexical scoping". There are a few other declarators, -## (`our`, `state`, ..., ) which we'll see later. This is called -## "lexical scoping", where in inner blocks, you can access variables from -## outer blocks. -my $file_scoped = 'Foo'; -sub outer { - my $outer_scoped = 'Bar'; - sub inner { - say "$file_scoped $outer_scoped"; - } - &inner; # return the function -} -outer()(); #=> 'Foo Bar' - -## As you can see, `$file_scoped` and `$outer_scoped` were captured. -## But if we were to try and use `$outer_scoped` outside the `outer` sub, -## the variable would be undefined (and you'd get a compile time error). -``` - -## Twigils - -```perl6 -## There are many special `twigils` (composed sigils) in Perl 6. Twigils -## define the variables' scope. -## The * and ? twigils work on standard variables: -## * Dynamic variable -## ? Compile-time variable -## The ! and the . twigils are used with Perl 6's objects: -## ! Attribute (instance attribute) -## . Method (not really a variable) - -## `*` twigil: Dynamic Scope -## These variables use the `*` twigil to mark dynamically-scoped variables. -## Dynamically-scoped variables are looked up through the caller, not through -## the outer scope. - -my $*dyn_scoped_1 = 1; -my $*dyn_scoped_2 = 10; - -sub say_dyn { - say "$*dyn_scoped_1 $*dyn_scoped_2"; -} - -sub call_say_dyn { - my $*dyn_scoped_1 = 25; # Defines $*dyn_scoped_1 only for this sub. - $*dyn_scoped_2 = 100; # Will change the value of the file scoped variable. - say_dyn(); #=> 25 100, $*dyn_scoped 1 and 2 will be looked - # for in the call. - # It uses the value of $*dyn_scoped_1 from inside - # this sub's lexical scope even though the blocks - # aren't nested (they're call-nested). -} -say_dyn(); #=> 1 10 -call_say_dyn(); #=> 25 100 - # Uses $*dyn_scoped_1 as defined in call_say_dyn even though - # we are calling it from outside. -say_dyn(); #=> 1 100 We changed the value of $*dyn_scoped_2 in - # call_say_dyn so now its value has changed. -``` - -## Object Model - -```perl6 -## To call a method on an object, add a dot followed by the method name: -## `$object.method` - -## Classes are declared with the `class` keyword. Attributes are declared -## with the `has` keyword, and methods declared with the `method` keyword. - -## Every attribute that is private uses the ! twigil. For example: `$!attr`. -## Immutable public attributes use the `.` twigil which creates a read-only -## method named after the attribute. In fact, declaring an attribute with `.` -## is equivalent to declaring the same attribute with `!` and then creating -## a read-only method with the attribute's name. However, this is done for us -## by Perl 6 automatically. The easiest way to remember the `$.` twigil is -## by comparing it to how methods are called. - -## Perl 6's object model ("SixModel") is very flexible, and allows you to -## dynamically add methods, change semantics, etc... Unfortunately, these will -## not all be covered here, and you should refer to: -## https://docs.perl6.org/language/objects.html. - -class Human { - has Str $.name; # `$.name` is immutable but with an accessor method. - has Str $.bcountry; # Use `$!bcountry` to modify it inside the class. - has Str $.ccountry is rw; # This attribute can be modified from outside. - has Int $!age = 0; # A private attribute with default value. - - method birthday { - $!age += 1; # Add a year to human's age - } - - method get-age { - return $!age; - } - - # This method is private to the class. Note the `!` before the - # method's name. - method !do-decoration { - return "$!name was born in $!bcountry and now lives in $!ccountry." - } - - # This method is public, just like `birthday` and `get-age`. - method get-info { - self.do-decoration; # Invoking a method on `self` inside the class. - # Use `self!priv-method` for private method. - # Use `self.publ-method` for public method. - } -}; - -## Create a new instance of Human class. -## Note: you can't set private-attribute from here (more later on). -my $person1 = Human.new( - name => "Jord", - bcountry = "Togo", - ccountry => "Togo" -); - -say $person1.name; #=> Jord -say $person1.bcountry; #=> Togo -say $person1.ccountry; #=> Togo - - -# $person1.bcountry = "Mali"; # This fails, because the `has $.bcountry` - # is immutable. Jord can't change his birthplace. -$person1.ccountry = "France"; # This works because the `$.ccountry` is mutable - # (`is rw`). Now Jord's current country is France. - -# Calling methods on the instance objects. -$person1.birthday; #=> 1 -$person1.get-info; #=> Jord was born in Togo and now lives in France. -$person1.do-decoration; # This fails since the method `do-decoration` is - # private. -``` - -### Object Inheritance - -```perl6 -## Perl 6 also has inheritance (along with multiple inheritance). While -## methods are inherited, submethods are not. Submethods are useful for -## object construction and destruction tasks, such as BUILD, or methods that -## must be overridden by subtypes. We will learn about BUILD later on. - -class Parent { - has $.age; - has $.name; - - # This submethod won't be inherited by the Child class. - submethod favorite-color { - say "My favorite color is Blue"; - } - - # This method is inherited - method talk { say "Hi, my name is $!name" } -} - -# Inheritance uses the `is` keyword -class Child is Parent { - method talk { say "Goo goo ga ga" } - # This shadows Parent's `talk` method. - # This child hasn't learned to speak yet! -} - -my Parent $Richard .= new(age => 40, name => 'Richard'); -$Richard.favorite-color; #=> "My favorite color is Blue" -$Richard.talk; #=> "Hi, my name is Richard" -## $Richard is able to access the submethod and he knows how to say his name. - -my Child $Madison .= new(age => 1, name => 'Madison'); -$Madison.talk; #=> "Goo goo ga ga", due to the overridden method. -# $Madison.favorite-color # does not work since it is not inherited. - -## When you use `my T $var`, `$var` starts off with `T` itself in it, -## so you can call `new` on it. -## (`.=` is just the dot-call and the assignment operator: -## `$a .= b` is the same as `$a = $a.b`) -## Also note that `BUILD` (the method called inside `new`) -## will set parent's properties too, so you can pass `val => 5`. -``` - -### Roles, or Mixins - -```perl6 -## Roles are supported too (which are called Mixins in other languages) -role PrintableVal { - has $!counter = 0; - method print { - say $.val; - } -} - -## you "apply" a role (or mixin) with `does` keyword: -class Item does PrintableVal { - has $.val; - - ## When `does`-ed, a `role` literally "mixes in" the class: - ## the methods and attributes are put together, which means a class - ## can access the private attributes/methods of its roles (but - ## not the inverse!): - method access { - say $!counter++; - } - - ## However, this: - ## method print {} - ## is ONLY valid when `print` isn't a `multi` with the same dispatch. - ## (this means a parent class can shadow a child class's `multi print() {}`, - ## but it's an error if a role does) - - ## NOTE: You can use a role as a class (with `is ROLE`). In this case, - ## methods will be shadowed, since the compiler will consider `ROLE` - ## to be a class. -} -``` - -## Exceptions - -```perl6 -## Exceptions are built on top of classes, in the package `X` (like `X::IO`). -## In Perl6 exceptions are automatically 'thrown': -open 'foo'; #=> Failed to open file foo: no such file or directory -## It will also print out what line the error was thrown at -## and other error info. - -## You can throw an exception using `die`: -die 'Error!'; #=> Error! - -## Or more explicitly: -X::AdHoc.new(payload => 'Error!').throw; #=> Error! - -## In Perl 6, `orelse` is similar to the `or` operator, except it only matches -## undefined variables instead of anything evaluating as `False`. -## Undefined values include: `Nil`, `Mu` and `Failure` as well as `Int`, `Str` -## and other types that have not been initialized to any value yet. -## You can check if something is defined or not using the defined method: -my $uninitialized; -say $uninitiazilzed.defined; #=> False - -## When using `orelse` it will disarm the exception and alias $_ to that -## failure. This will prevent it to being automatically handled and printing -## lots of scary error messages to the screen. We can use the `exception` -## method on the `$_` variable to access the exception -open 'foo' orelse say "Something happened {.exception}"; - -## This also works: -open 'foo' orelse say "Something happened $_"; #=> Something happened - #=> Failed to open file foo: no such file or directory -## Both of those above work but in case we get an object from the left side -## that is not a failure we will probably get a warning. We see below how we -## can use try` and `CATCH` to be more specific with the exceptions we catch. -``` - -### Using `try` and `CATCH` - -```perl6 -## By using `try` and `CATCH` you can contain and handle exceptions without -## disrupting the rest of the program. The `try` block will set the last -## exception to the special variable `$!` (known as the error variable). -## Note: This has no relation to $!variables seen inside class definitions. - -try open 'foo'; -say "Well, I tried! $!" if defined $!; -#=> Well, I tried! Failed to open file foo: no such file or directory - -## Now, what if we want more control over handling the exception? -## Unlike many other languages, in Perl 6, you put the `CATCH` block *within* -## the block to `try`. Similar to how the `$_` variable was set when we -## 'disarmed' the exception with `orelse`, we also use `$_` in the CATCH block. -## Note: The `$!` variable is only set *after* the `try` block has caught an -## exception. By default, a `try` block has a `CATCH` block of its own that -## catches any exception (`CATCH { default {} }`). - -try { - my $a = (0 %% 0); - CATCH { - say "Something happened: $_" - } -} -#=> Something happened: Attempt to divide by zero using infix:<%%> - -## You can redefine it using `when`s (and `default`) to handle the exceptions -## you want to catch explicitly: - -try { - open 'foo'; - CATCH { - # In the `CATCH` block, the exception is set to the $_ variable. - when X::AdHoc { - say "Error: $_" - } - when X::Numeric::DivideByZero { - say "Error: $_"; - } - ## Any other exceptions will be re-raised, since we don't have a `default`. - ## Basically, if a `when` matches (or there's a `default`), the - ## exception is marked as "handled" so as to prevent its re-throw - ## from the `CATCH` block. You still can re-throw the exception (see below) - ## by hand. - } -} -#=>Error: Failed to open file /dir/foo: no such file or directory - -## There are also some subtleties to exceptions. Some Perl 6 subs return a -## `Failure`, which is a wrapper around an `Exception` object which is -## "unthrown". They're not thrown until you try to use the variables containing -## them unless you call `.Bool`/`.defined` on them - then they're handled. -## (the `.handled` method is `rw`, so you can mark it as `False` back yourself) -## You can throw a `Failure` using `fail`. Note that if the pragma `use fatal` -## is on, `fail` will throw an exception (like `die`). - -fail "foo"; # We're not trying to access the value, so no problem. -try { - fail "foo"; - CATCH { - default { - say "It threw because we tried to get the fail's value!" - } - } -} - -## There is also another kind of exception: Control exceptions. -## Those are "good" exceptions, which happen when you change your program's -## flow, using operators like `return`, `next` or `last`. -## You can "catch" those with `CONTROL` (not 100% working in Rakudo yet). -``` - -## Packages - -```perl6 -## Packages are a way to reuse code. Packages are like "namespaces", and any -## element of the six model (`module`, `role`, `class`, `grammar`, `subset` and -## `enum`) are actually packages. (Packages are the lowest common denominator) -## Packages are important - especially as Perl is well-known for CPAN, -## the Comprehensive Perl Archive Network. - -## You can use a module (bring its declarations into scope) with -## the `use` keyword: -use JSON::Tiny; # if you installed Rakudo* or Panda, you'll have this module -say from-json('[1]').perl; #=> [1] - -## You should not declare packages using the `package` keyword (unlike Perl 5). -## Instead, use `class Package::Name::Here;` to declare a class, or if you only -## want to export variables/subs, you can use `module` instead. - -module Hello::World { # bracketed form - # If `Hello` doesn't exist yet, it'll just be a "stub", - # that can be redeclared as something else later. - - # ... declarations here ... -} - -unit module Parse::Text; # file-scoped form which extends until - # the end of the file - -grammar Parse::Text::Grammar { - # A grammar is a package, which you could `use`. - # You will learn more about grammars in the regex section -} - -## As said before, any part of the six model is also a package. -## Since `JSON::Tiny` uses its own `JSON::Tiny::Actions` class, you can use it: -my $actions = JSON::Tiny::Actions.new; - -## We'll see how to export variables and subs in the next part. -``` - -## Declarators - -```perl6 -## In Perl 6, you get different behaviors based on how you declare a variable. -## You've already seen `my` and `has`, we'll now explore the others. - -## `our` - these declarations happen at `INIT` time -- (see "Phasers" below). -## It's like `my`, but it also creates a package variable. All packagish -## things such as `class`, `role`, etc. are `our` by default. - -module Var::Increment { - our $our-var = 1; # Note: `our`-declared variables cannot be typed. - my $my-var = 22; - - our sub Inc { - our sub available { # If you try to make inner `sub`s `our`... - # ... Better know what you're doing (Don't !). - say "Don't do that. Seriously. You'll get burned."; - } - - my sub unavailable { # `sub`s are `my`-declared by default - say "Can't access me from outside, I'm 'my'!"; - } - say ++$our-var; # Increment the package variable and output its value - } - -} - -say $Var::Increment::our-var; #=> 1, this works! -say $Var::Increment::my-var; #=> (Any), this will not work! - -Var::Increment::Inc; #=> 2 -Var::Increment::Inc; #=> 3 , notice how the value of $our-var was - # retained. -Var::Increment::unavailable; #=> Could not find symbol '&unavailable' - -## `constant` - these declarations happen at `BEGIN` time. You can use -## the `constant` keyword to declare a compile-time variable/symbol: -constant Pi = 3.14; -constant $var = 1; - -## And if you're wondering, yes, it can also contain infinite lists. -constant why-not = 5, 15 ... *; -say why-not[^5]; #=> 5 15 25 35 45 - -## `state` - these declarations happen at run time, but only once. State -## variables are only initialized one time. In other languages such as C -## they exist as `static` variables. -sub fixed-rand { - state $val = rand; - say $val; -} -fixed-rand for ^10; # will print the same number 10 times - -## Note, however, that they exist separately in different enclosing contexts. -## If you declare a function with a `state` within a loop, it'll re-create the -## variable for each iteration of the loop. See: -for ^5 -> $a { - sub foo { - state $val = rand; # This will be a different value for - # every value of `$a` - } - for ^5 -> $b { - say foo; # This will print the same value 5 times, - # but only 5. Next iteration will re-run `rand`. - } -} -``` - -## Phasers - -```perl6 -## Phasers in Perl 6 are blocks that happen at determined points of time in -## your program. They are called phasers because they mark a change in the -## phase of a program. For example, when the program is compiled, a for loop -## runs, you leave a block, or an exception gets thrown (The `CATCH` block is -## actually a phaser!). Some of them can be used for their return values, -## some of them can't (those that can have a "[*]" in the beginning of their -## explanation text). Let's have a look! - -## Compile-time phasers -BEGIN { say "[*] Runs at compile time, as soon as possible, only once" } -CHECK { say "[*] Runs at compile time, as late as possible, only once" } - -## Run-time phasers -INIT { say "[*] Runs at run time, as soon as possible, only once" } -END { say "Runs at run time, as late as possible, only once" } - -## Block phasers -ENTER { say "[*] Runs everytime you enter a block, repeats on loop blocks" } -LEAVE { - say "Runs everytime you leave a block, even when an exception - happened. Repeats on loop blocks." -} - -PRE { - say "Asserts a precondition at every block entry, - before ENTER (especially useful for loops)"; - say "If this block doesn't return a truthy value, - an exception of type X::Phaser::PrePost is thrown."; -} - -## Example: -for 0..2 { - PRE { $_ > 1 } # This is going to blow up with "Precondition failed" -} - -POST { - say "Asserts a postcondition at every block exit, - after LEAVE (especially useful for loops)"; - say "If this block doesn't return a truthy value, - an exception of type X::Phaser::PrePost is thrown, like PRE."; -} - -for 0..2 { - POST { $_ < 2 } # This is going to blow up with "Postcondition failed" -} - -## Block/exceptions phasers -sub { - KEEP { say "Runs when you exit a block successfully - (without throwing an exception)" } - UNDO { say "Runs when you exit a block unsuccessfully - (by throwing an exception)" } -} - -## Loop phasers -for ^5 { - FIRST { say "[*] The first time the loop is run, before ENTER" } - NEXT { say "At loop continuation time, before LEAVE" } - LAST { say "At loop termination time, after LEAVE" } -} - -## Role/class phasers -COMPOSE { "When a role is composed into a class. /!\ NOT YET IMPLEMENTED" } - -## They allow for cute tricks or clever code...: -say "This code took " ~ (time - CHECK time) ~ "s to compile"; - -## ... or clever organization: -sub do-db-stuff { - $db.start-transaction; # start a new transaction - KEEP $db.commit; # commit the transaction if all went well - UNDO $db.rollback; # or rollback if all hell broke loose -} -``` - -## Statement prefixes - -```perl6 -## Those act a bit like phasers: they affect the behavior of the following -## code. Though, they run in-line with the executable code, so they're in -## lowercase. (`try` and `start` are theoretically in that list, but explained -## elsewhere) Note: all of these (except start) don't need explicit curly -## braces `{` and `}`. - -## `do` - (which you already saw) runs a block or a statement as a term. -## Normally you cannot use a statement as a value (or "term"). `do` helps us -## do it. - -# my $value = if True { 1 } # this fails since `if` is a statement -my $a = do if True { 5 } # with `do`, `if` is now a term returning a value - -## `once` - makes sure a piece of code only runs once. -for ^5 { - once say 1 -}; #=> 1, only prints ... once - -## Similar to `state`, they're cloned per-scope. -for ^5 { - sub { once say 1 }() -}; #=> 1 1 1 1 1, prints once per lexical scope. - -## `gather` - co-routine thread. The `gather` constructs allows us to `take` -## several values from an array/list, much like `do`. -say gather for ^5 { - take $_ * 3 - 1; - take $_ * 3 + 1; -} -#=> -1 1 2 4 5 7 8 10 11 13 - -say join ',', gather if False { - take 1; - take 2; - take 3; -} -# Doesn't print anything. - -## `eager` - evaluates a statement eagerly (forces eager context) -## Don't try this at home: -# eager 1..*; # this will probably hang for a while (and might crash ...). -## But consider: -constant thrice = gather for ^3 { say take $_ }; # Doesn't print anything -## versus: -constant thrice = eager gather for ^3 { say take $_ }; #=> 0 1 2 -``` - -## Iterables - -```perl6 -## Iterables are objects that can be iterated over which are -## are similar to the `for` construct. - -## `flat` - flattens iterables. -say (1, 10, (20, 10) ); #=> (1 10 (20 10)), notice how neste lists are - # preserved -say (1, 10, (20, 10) ).flat; #=> (1 10 20 10), now the iterable is flat - -## - `lazy` - defers actual evaluation until value is fetched by forcing -## lazy context. -my @lazy-array = (1..100).lazy; -say @lazy-array.is-lazy; #=> True, check for laziness with the `is-lazy` method. -say @lazy-array; #=> [...] List has not been iterated on! -my @lazy-array { .print }; # This works and will only do as much work as - # is needed. - -# ( **TODO** explain that gather/take and map are all lazy) - -## `sink` - an `eager` that discards the results by forcing sink context. -constant nilthingie = sink for ^3 { .say } #=> 0 1 2 -say nilthingie.perl; #=> Nil - -## `quietly` - suppresses warnings in blocks. -quietly { warn 'This is a warning!' }; #=> No output - -## `contend` - attempts side effects under STM -## Not yet implemented! -``` - -## More operators thingies! - -```perl6 -## Everybody loves operators! Let's get more of them. - -## The precedence list can be found here: -## https://docs.perl6.org/language/operators#Operator_Precedence -## But first, we need a little explanation about associativity: - -## Binary operators: -$a ! $b ! $c; # with a left-associative `!`, this is `($a ! $b) ! $c` -$a ! $b ! $c; # with a right-associative `!`, this is `$a ! ($b ! $c)` -$a ! $b ! $c; # with a non-associative `!`, this is illegal -$a ! $b ! $c; # with a chain-associative `!`, this is `($a ! $b) and ($b ! $c)` -$a ! $b ! $c; # with a list-associative `!`, this is `infix:<>` - -## Unary operators: -!$a! # with left-associative `!`, this is `(!$a)!` -!$a! # with right-associative `!`, this is `!($a!)` -!$a! # with non-associative `!`, this is illegal -``` - -### Create your own operators! - -```perl6 -## Okay, you've been reading all of that, so you might want to try something -## more exciting?! I'll tell you a little secret (or not-so-secret): -## In Perl 6, all operators are actually just funny-looking subroutines. - -## You can declare an operator just like you declare a sub: -# prefix refers to the operator categories (prefix, infix, postfix, etc). -sub prefix:<win>( $winner ) { - say "$winner Won!"; -} -win "The King"; #=> The King Won! - # (prefix means 'before') - -## you can still call the sub with its "full name": -say prefix:<!>(True); #=> False -prefix:<win>("The Queen"); #=> The Queen Won! - -sub postfix:<!>( Int $n ) { - [*] 2..$n; # using the reduce meta-operator... See below ;-)! -} -say 5!; #=> 120 - # Postfix operators ('after') have to come *directly* after the term. - # No whitespace. You can use parentheses to disambiguate, i.e. `(5!)!` - -sub infix:<times>( Int $n, Block $r ) { # infix ('between') - for ^$n { - $r(); # You need the explicit parentheses to call the function in `$r`, - # else you'd be referring at the variable itself, like with `&r`. - } -} -3 times -> { say "hello" }; #=> hello - #=> hello - #=> hello -## It's recommended to put spaces around your -## infix operator calls. - -## For circumfix and post-circumfix ones -sub circumfix:<[ ]>( Int $n ) { - $n ** $n -} -say [5]; #=> 3125 - # circumfix means 'around'. Again, no whitespace. - -sub postcircumfix:<{ }>( Str $s, Int $idx ) { - ## post-circumfix is 'after a term, around something' - $s.substr($idx, 1); -} -say "abc"{1}; #=> b - # after the term `"abc"`, and around the index (1) - -## This really means a lot -- because everything in Perl 6 uses this. -## For example, to delete a key from a hash, you use the `:delete` adverb -## (a simple named argument underneath): -%h{$key}:delete; -## equivalent to: -postcircumfix:<{ }>( %h, $key, :delete ); # (you can call operators like this) - -## It's *all* using the same building blocks! Syntactic categories -## (prefix infix ...), named arguments (adverbs), ..., etc. used to build -## the language - are available to you. Obviously, you're advised against -## making an operator out of *everything* -- with great power comes great -## responsibility. -``` - -### Meta operators! - -```perl6 -## Oh boy, get ready!. Get ready, because we're delving deep into the rabbit's -## hole, and you probably won't want to go back to other languages after -## reading this. (I'm guessing you don't want to go back at this point but -## let's continue, for the journey is long and enjoyable!). - -## Meta-operators, as their name suggests, are *composed* operators. -## Basically, they're operators that act on another operators. - -## The reduce meta-operator is a prefix meta-operator that takes a binary -## function and one or many lists. If it doesn't get passed any argument, -## it either returns a "default value" for this operator (a meaningless value) -## or `Any` if there's none (examples below). Otherwise, it pops an element -## from the list(s) one at a time, and applies the binary function to the last -## result (or the list's first element) and the popped element. - -## To sum a list, you could use the reduce meta-operator with `+`, i.e.: -say [+] 1, 2, 3; #=> 6, equivalent to (1+2)+3. - -## To multiply a list -say [*] 1..5; #=> 120, equivalent to ((((1*2)*3)*4)*5). - -## You can reduce with any operator, not just with mathematical ones. -## For example, you could reduce with `//` to get first defined element -## of a list: -say [//] Nil, Any, False, 1, 5; #=> False - # (Falsey, but still defined) -## Or with relational operators, i.e., `>` to check elements of a list -## are ordered accordingly: -say say [>] 234, 156, 6, 3, -20; #=> True - -## Default value examples: -say [*] (); #=> 1 -say [+] (); #=> 0 - # meaningless values, since N*1=N and N+0=N. -say [//]; #=> (Any) - # There's no "default value" for `//`. - -## You can also call it with a function you made up, using double brackets: -sub add($a, $b) { $a + $b } -say [[&add]] 1, 2, 3; #=> 6 - -## The zip meta-operator is an infix meta-operator that also can be used as a -## "normal" operator. It takes an optional binary function (by default, it -## just creates a pair), and will pop one value off of each array and call -## its binary function on these until it runs out of elements. It returns an -## array with all of these new elements. -say (1, 2) Z (3, 4); #=> ((1, 3), (2, 4)), since by default the function - # makes an array. -say 1..3 Z+ 4..6; #=> (5, 7, 9), using the custom infix:<+> function - -## Since `Z` is list-associative (see the list above), -## you can use it on more than one list -(True, False) Z|| (False, False) Z|| (False, False); # (True, False) - -## And, as it turns out, you can also use the reduce meta-operator with it: -[Z||] (True, False), (False, False), (False, False); # (True, False) - - -## And to end the operator list: - -## The sequence operator is one of Perl 6's most powerful features: -## it's composed of first, on the left, the list you want Perl 6 to deduce from -## (and might include a closure), and on the right, a value or the predicate -## that says when to stop (or a Whatever Star for a lazy infinite list). - -my @list = 1, 2, 3...10; # basic arithmetic sequence -# my @list = 1, 3, 6...10; # this dies because Perl 6 can't figure out the end -my @list = 1, 2, 3...^10; # as with ranges, you can exclude the last element - # (the iteration ends when the predicate matches). -my @list = 1, 3, 9...* > 30; # you can use a predicate (with the Whatever Star). -my @list = 1, 3, 9 ... { $_ > 30 }; # (equivalent to the above - # using a block here). - -my @fib = 1, 1, *+* ... *; # lazy infinite list of fibonacci sequence, - # computed using a closure! -my @fib = 1, 1, -> $a, $b { $a + $b } ... *; # (equivalent to the above) -my @fib = 1, 1, { $^a + $^b } ... *; # (also equivalent to the above) -## $a and $b will always take the previous values, meaning here -## they'll start with $a = 1 and $b = 1 (values we set by hand), -## then $a = 1 and $b = 2 (result from previous $a+$b), and so on. - -say @fib[^10]; #=> 1 1 2 3 5 8 13 21 34 55 - # (using a range as the index) -## Note: as for ranges, once reified, elements aren't re-calculated. -## That's why `@primes[^100]` will take a long time the first time you print -## it, then will be instateneous. -``` - -## Regular Expressions - -```perl6 -## I'm sure a lot of you have been waiting for this one. Well, now that you know -## a good deal of Perl 6 already, we can get started. First off, you'll have to -## forget about "PCRE regexps" (perl-compatible regexps). -## -## IMPORTANT: Don't skip them because you know PCRE. They're different. Some -## things are the same (like `?`, `+`, and `*`), but sometimes the semantics -## change (`|`). Make sure you read carefully, because you might trip over a -## new behavior. -## -## Perl 6 has many features related to RegExps. After all, Rakudo parses itself. -## We're first going to look at the syntax itself, then talk about grammars -## (PEG-like), differences between `token`, `regex` and `rule` declarators, -## and some more. Side note: you still have access to PCRE regexps using the -## `:P5` modifier which we won't be discussing this in this tutorial, though. -## -## In essence, Perl 6 natively implements PEG ("Parsing Expression Grammars"). -## The pecking order for ambiguous parses is determined by a multi-level -## tie-breaking test: -## - Longest token matching: `foo\s+` beats `foo` (by 2 or more positions) -## - Longest literal prefix: `food\w*` beats `foo\w*` (by 1) -## - Declaration from most-derived to less derived grammars -## (grammars are actually classes) -## - Earliest declaration wins -say so 'a' ~~ /a/; #=> True -say so 'a' ~~ / a /; #=> True, more readable with some spaces! - -## In all our examples, we're going to use the smart-matching operator against -## a regexp. We're converting the result using `so` to a Boolean value because, -## in fact, it's returning a `Match` object. They know how to respond to list -## indexing, hash indexing, and return the matched string. The results of the -## match are available in the `$/` variable (implicitly lexically-scoped). You -## can also use the capture variables which start at 0: `$0`, `$1', `$2`... -## -## You can also note that `~~` does not perform start/end checking, meaning -## the regexp can be matched with just one character of the string. We'll -## explain later how you can do it. - -## In Perl 6, you can have any alphanumeric as a literal, everything else has -## to be escaped by using a backslash or quotes. -say so 'a|b' ~~ / a '|' b /; #=> `True`, it wouldn't mean the same thing if - # `|` wasn't escaped. -say so 'a|b' ~~ / a \| b /; #=> `True`, another way to escape it. - -## The whitespace in a regexp is actually not significant, unless you use the -## `:s` (`:sigspace`, significant space) adverb. -say so 'a b c' ~~ / a b c /; #=> `False`, space is not significant here! -say so 'a b c' ~~ /:s a b c /; #=> `True`, we added the modifier `:s` here. - -## If we use only one space between strings in a regex, Perl 6 will warn us: -say so 'a b c' ~~ / a b c /; #=> `False`, with warning about space -say so 'a b c' ~~ / a b c /; #=> `False` - -## Please use quotes or :s (:sigspace) modifier (or, to suppress this warning, -## omit the space, or otherwise change the spacing). To fix this and make the -## spaces less ambiguous, either use at least two spaces between strings -## or use the `:s` adverb. - -## As we saw before, we can embed the `:s` inside the slash delimiters, but we -## can also put it outside of them if we specify `m` for 'match': -say so 'a b c' ~~ m:s/a b c/; #=> `True` - -## By using `m` to specify 'match', we can also use delimiters other than -## slashes: -say so 'abc' ~~ m{a b c}; #=> `True` -say so 'abc' ~~ m[a b c]; #=> `True` -# m/.../ is equivalent to /.../ - -## Use the :i adverb to specify case insensitivity: -say so 'ABC' ~~ m:i{a b c}; #=> `True` - -## However, whitespace is important as for how modifiers are applied ( -## (which you'll see just below) ... - -## Quantifying - `?`, `+`, `*` and `**`. -## `?` - zero or one match -so 'ac' ~~ / a b c /; #=> `False` -so 'ac' ~~ / a b? c /; #=> `True`, the "b" matched 0 times. -so 'abc' ~~ / a b? c /; #=> `True`, the "b" matched 1 time. - -## ...As you read before, whitespace is important because it determines which -## part of the regexp is the target of the modifier: -so 'def' ~~ / a b c? /; #=> `False`, only the `c` is optional -so 'def' ~~ / a b? c /; #=> `False`, whitespace is not significant -so 'def' ~~ / 'abc'? /; #=> `True`, the whole "abc" group is optional - -## Here (and below) the quantifier applies only to the `b` - -## `+` - one or more matches -so 'ac' ~~ / a b+ c /; #=> `False`, `+` wants at least one matching -so 'abc' ~~ / a b+ c /; #=> `True`, one is enough -so 'abbbbc' ~~ / a b+ c /; #=> `True`, matched 4 "b"s - -## `*` - zero or more matches -so 'ac' ~~ / a b* c /; #=> `True`, they're all optional. -so 'abc' ~~ / a b* c /; #=> `True` -so 'abbbbc' ~~ / a b* c /; #=> `True` -so 'aec' ~~ / a b* c /; #=> `False`. "b"(s) are optional, not replaceable. - -## `**` - (Unbound) Quantifier -## If you squint hard enough, you might understand why exponentation is used -## for quantity. -so 'abc' ~~ / a b**1 c /; #=> `True`, (exactly one time) -so 'abc' ~~ / a b**1..3 c /; #=> `True`, (one to three times) -so 'abbbc' ~~ / a b**1..3 c /; #=> `True` -so 'abbbbbbc' ~~ / a b**1..3 c /; #=> `False, (too much) -so 'abbbbbbc' ~~ / a b**3..* c /; #=> `True`, (infinite ranges are okay) - -## `<[]>` - Character classes -## Character classes are the equivalent of PCRE's `[]` classes, but they use a -## more perl6-ish syntax: -say 'fooa' ~~ / f <[ o a ]>+ /; #=> 'fooa' - -## You can use ranges: -say 'aeiou' ~~ / a <[ e..w ]> /; #=> 'ae' - -## Just like in normal regexes, if you want to use a special character, escape -## it (the last one is escaping a space which would be equivalent to using -## ' '): -say 'he-he !' ~~ / 'he-' <[ a..z \! \ ]> + /; #=> 'he-he !' - -## You'll get a warning if you put duplicate names (which has the nice effect -## of catching the raw quoting): -'he he' ~~ / <[ h e ' ' ]> /; -# Warns "Repeated character (') unexpectedly found in character class" - -## You can also negate character classes... (`<-[]>` equivalent to `[^]` in PCRE) -so 'foo' ~~ / <-[ f o ]> + /; #=> False - -## ... and compose them: -so 'foo' ~~ / <[ a..z ] - [ f o ]> + /; #=> `False`, (any letter except f and o) -so 'foo' ~~ / <-[ a..z ] + [ f o ]> + /; #=> `True`, (no letter except f and o) -so 'foo!' ~~ / <-[ a..z ] + [ f o ]> + /; #=> `True`, (the + doesn't replace the - # left part) -``` - -### Grouping and capturing - -```perl6 -## Group: you can group parts of your regexp with `[]`. Unlike PCRE's `(?:)`, -## these groups are *not* captured. -so 'abc' ~~ / a [ b ] c /; # `True`. The grouping does pretty much nothing -so 'foo012012bar' ~~ / foo [ '01' <[0..9]> ] + bar /; - -## The previous line returns `True`. The regex matches "012" 1 or more time -## (achieved by the the `+` applied to the group). - -## But this does not go far enough, because we can't actually get back what -## we matched. - -## Capture: The results of a regexp can be *captured* by using parentheses. -so 'fooABCABCbar' ~~ / foo ( 'A' <[A..Z]> 'C' ) + bar /; # `True`. (using `so` - # here, `$/` below) - -## So, starting with the grouping explanations. -## As we said before, our `Match` object is stored inside the `$/` variable: -say $/; # Will either print some weird stuff or `Nil` if nothing matched. - -## As we also said before, it has array indexing: -say $/[0]; #=> ｢ABC｣ ｢ABC｣ - # These corner brackets are `Match` objects. - # Here, we have an array of these. -say $0; # The same as above. - -## Our capture is `$0` because it's the first and only one capture in the -## regexp. You might be wondering why it's an array, and the answer is simple: -## Some captures (indexed using `$0`, `$/[0]` or a named one) will be an array -## if and only if they can have more than one element. Thus any capture with -## `*`, `+` and `**` (whatever the operands), but not with `?`. -## Let's use examples to see that: - -## Note: We quoted A B C to demonstrate that the whitespace between them isn't -## significant. If we want the whitespace to *be* significant there, we -## can use the :sigspace modifier. -say so 'fooABCbar' ~~ / foo ( "A" "B" "C" )? bar /; #=> `True` -say $/[0]; #=> ｢ABC｣ -say $0.WHAT; #=> (Match) - # There can't be more than one, so it's only a single match object. -say so 'foobar' ~~ / foo ( "A" "B" "C" )? bar /; #=> True -say $0.WHAT; #=> (Any) - # This capture did not match, so it's empty -so 'foobar' ~~ / foo ( "A" "B" "C" ) ** 0..1 bar /; #=> `True` -say $0.WHAT; #=> (Array) - # A specific quantifier will always capture an Array, - # be a range or a specific value (even 1). - -## The captures are indexed per nesting. This means a group in a group will be -## nested under its parent group: `$/[0][0]`, for this code: -'hello-~-world' ~~ / ( 'hello' ( <[ \- \~ ]> + ) ) 'world' /; -say $/[0].Str; #=> hello~ -say $/[0][0].Str; #=> ~ - -## This stems from a very simple fact: `$/` does not contain strings, integers -## or arrays, it only contains Match objects. These contain the `.list`, `.hash` -## and `.Str` methods but you can also just use `match<key>` for hash access -## and `match[idx]` for array access. -say $/[0].list.perl; #=> (Match.new(...),).list - # We can see it's a list of Match objects. These contain - # a bunch of info: where the match started/ended, - # the "ast" (see actions later), etc. - # You'll see named capture below with grammars. - -## Alternation - the `or` of regexps -## WARNING: They are DIFFERENT from PCRE regexps. -say so 'abc' ~~ / a [ b | y ] c /; #=> `True`. Either "b" or "y". -say so 'ayc' ~~ / a [ b | y ] c /; #=> `True`. Obviously enough... - -## The difference between this `|` and the one you're used to is -## LTM ("Longest Token Matching"). This means that the engine will always -## try to match as much as possible in the string. -say 'foo' ~~ / fo | foo /; #=> `foo`, instead of `fo`, because it's longer. - -## To decide which part is the "longest", it first splits the regex in -## two parts: -## The "declarative prefix" (the part that can be statically analyzed) -## and the procedural parts: -## - The declarative prefixes include alternations (`|`), conjunctions (`&`), -## sub-rule calls (not yet introduced), literals, characters classes and -## quantifiers. -## - The procedural part include everything else: back-references, -## code assertions, and other things that can't traditionnaly be represented -## by normal regexps. -## -## Then, all the alternatives are tried at once, and the longest wins. -## Examples: -## DECLARATIVE | PROCEDURAL -/ 'foo' \d+ [ <subrule1> || <subrule2> ] /; -## DECLARATIVE (nested groups are not a problem) -/ \s* [ \w & b ] [ c | d ] /; -## However, closures and recursion (of named regexps) are procedural. -## There are also more complicated rules, like specificity (literals win over -## character classes). - -## Note: the first-matching `or` still exists, but is now spelled `||` -say 'foo' ~~ / fo || foo /; #=> `fo` now. -``` - -## Extra: the MAIN subroutine - -```perl6 -## The `MAIN` subroutine is called when you run a Perl 6 file directly. It's -## very powerful, because Perl 6 actually parses the arguments and pass them -## as such to the sub. It also handles named argument (`--foo`) and will even -## go as far as to autogenerate a `--help` flag. -sub MAIN($name) { - say "Hello, $name!"; -} -## This produces: -## $ perl6 cli.pl -## Usage: -## t.pl <name> - -## And since it's a regular Perl 6 sub, you can have multi-dispatch: -## (using a "Bool" for the named argument so that we can do `--replace` -## instead of `--replace=1`. The presence of `--replace` indicates truthness -## while its absence falseness). - -subset File of Str where *.IO.d; # convert to IO object to check the file exists - -multi MAIN('add', $key, $value, Bool :$replace) { ... } -multi MAIN('remove', $key) { ... } -multi MAIN('import', File, Str :$as) { ... } # omitting parameter name - -## This produces: -## $ perl6 cli.pl -## Usage: -## cli.p6 [--replace] add <key> <value> -## cli.p6 remove <key> -## cli.p6 [--as=<Str>] import <File> - -## As you can see, this is *very* powerful. It even went as far as to show inline -## the constants (the type is only displayed if the argument is `$`/is named). -``` - -## APPENDIX A: -### List of things - -```perl6 -## It's assumed by now you know the Perl6 basics. This section is just here to -## list some common operations, but which are not in the "main part" of the -## tutorial to avoid bloating it up. - -## Operators - -## Sort comparison - they return one value of the `Order` enum: `Less`, `Same` -## and `More` (which numerify to -1, 0 or +1 respectively). -1 <=> 4; # sort comparison for numerics -'a' leg 'b'; # sort comparison for string -$obj eqv $obj2; # sort comparison using eqv semantics - -## Generic ordering -3 before 4; # True -'b' after 'a'; # True - -## Short-circuit default operator - similar to `or` and `||`, but instead -## returns the first *defined* value: -say Any // Nil // 0 // 5; #=> 0 - -## Short-circuit exclusive or (XOR) - returns `True` if one (and only one) of -## its arguments is true -say True ^^ False; #=> True - -## Flip flops - these operators (`ff` and `fff`, equivalent to P5's `..` -## and `...`) are operators that take two predicates to test: They are `False` -## until their left side returns `True`, then are `True` until their right -## side returns `True`. Similar to ranges, you can exclude the iteration when -## it become `True`/`False` by using `^` on either side. Let's start with an -## example : -for <well met young hero we shall meet later> { - # by default, `ff`/`fff` smart-match (`~~`) against `$_`: - if 'met' ^ff 'meet' { # Won't enter the if for "met" - .say # (explained in details below). - } - - if rand == 0 ff rand == 1 { # compare variables other than `$_` - say "This ... probably will never run ..."; - } -} - -## This will print "young hero we shall meet" (excluding "met"): the flip-flop -## will start returning `True` when it first encounters "met" (but will still -## return `False` for "met" itself, due to the leading `^` on `ff`), until it -## sees "meet", which is when it'll start returning `False`. - -## The difference between `ff` (awk-style) and `fff` (sed-style) is that `ff` -## will test its right side right when its left side changes to `True`, and can -## get back to `False` right away (*except* it'll be `True` for the iteration -## that matched) while `fff` will wait for the next iteration to try its right -## side, once its left side changed: -.say if 'B' ff 'B' for <A B C B A>; #=> B B - # because the right-hand-side was tested - # directly (and returned `True`). - # "B"s are printed since it matched that - # time (it just went back to `False` - # right away). -.say if 'B' fff 'B' for <A B C B A>; #=> B C B - # The right-hand-side wasn't tested until - # `$_` became "C" - # (and thus did not match instantly). - -## A flip-flop can change state as many times as needed: -for <test start print it stop not printing start print again stop not anymore> { - .say if $_ eq 'start' ^ff^ $_ eq 'stop'; # exclude both "start" and "stop", - #=> "print it print again" -} - -## You might also use a Whatever Star, which is equivalent to `True` for the -## left side or `False` for the right: -for (1, 3, 60, 3, 40, 60) { # Note: the parenthesis are superfluous here - # (sometimes called "superstitious parentheses") - .say if $_ > 50 ff *; # Once the flip-flop reaches a number greater - # than 50, it'll never go back to `False` - #=> 60 3 40 60 -} - -## You can also use this property to create an `if` that'll not go through the -## first time: -for <a b c> { - .say if * ^ff *; # the flip-flop is `True` and never goes back to `False`, - # but the `^` makes it *not run* on the first iteration - #=> b c -} - -## The `===` operator is the value identity operator and uses `.WHICH` on the -## objects to compare them while `=:=` is the container identity operator -## and uses `VAR()` on the objects to compare them. -``` - -If you want to go further, you can: - - - Read the [Perl 6 Docs](https://docs.perl6.org/). This is a great - resource on Perl6. If you are looking for something, use the search bar. - This will give you a dropdown menu of all the pages referencing your search - term (Much better than using Google to find Perl 6 documents!). - - Read the [Perl 6 Advent Calendar](http://perl6advent.wordpress.com/). This - is a great source of Perl 6 snippets and explanations. If the docs don't - describe something well enough, you may find more detailed information here. - This information may be a bit older but there are many great examples and - explanations. Posts stopped at the end of 2015 when the language was declared - stable and Perl 6.c was released. - - Come along on `#perl6` at `irc.freenode.net`. The folks here are - always helpful. - - Check the [source of Perl 6's functions and - classes](https://github.com/rakudo/rakudo/tree/nom/src/core). Rakudo is - mainly written in Perl 6 (with a lot of NQP, "Not Quite Perl", a Perl 6 subset - easier to implement and optimize). - - Read [the language design documents](http://design.perl6.org). They explain - P6 from an implementor point-of-view, but it's still very interesting. diff --git a/pt-br/bash-pt.html.markdown b/pt-br/bash-pt.html.markdown index 3a48d994..86d1a8ea 100644 --- a/pt-br/bash-pt.html.markdown +++ b/pt-br/bash-pt.html.markdown @@ -33,7 +33,7 @@ diretamente no shell. # Exemplo simples de hello world: echo Hello World! -# Cada comando começa com uma nova linha, ou após um ponto virgula: +# Cada comando começa com uma nova linha, ou após um ponto e vírgula: echo 'Essa é a primeira linha'; echo 'Essa é a segunda linha' # A declaração de variáveis é mais ou menos assim @@ -41,14 +41,14 @@ Variavel="Alguma string" # Mas não assim: Variavel = "Alguma string" -# Bash interpretará Variavel como um comando e tentará executar e lhe retornar +# Bash interpretará Variavel como um comando e tentará executar e lhe retornará # um erro porque o comando não pode ser encontrado. # Ou assim: Variavel= 'Alguma string' -# Bash interpretará 'Alguma string' como um comando e tentará executar e lhe retornar +# Bash interpretará 'Alguma string' como um comando e tentará executar e lhe retornará # um erro porque o comando não pode ser encontrado. (Nesse caso a a parte 'Variavel=' -# é vista com uma declaração de variável valida apenas para o escopo do comando 'Uma string'). +# é vista com uma declaração de variável válida apenas para o escopo do comando 'Uma string'). # Usando a variável: echo $Variavel @@ -65,12 +65,12 @@ echo ${Variavel/Alguma/Uma} # Substring de uma variável Tamanho=7 echo ${Variavel:0:Tamanho} -# Isso retornará apenas os 7 primeiros caractéres da variável +# Isso retornará apenas os 7 primeiros caracteres da variável # Valor padrão de uma variável echo ${Foo:-"ValorPadraoSeFooNaoExistirOuEstiverVazia"} # Isso funciona para nulo (Foo=) e (Foo=""); zero (Foo=0) retorna 0. -# Note que isso apenas retornar o valor padrão e não mudar o valor da variável. +# Note que isso apenas retornará o valor padrão e não mudará o valor da variável. # Variáveis internas # Tem algumas variáveis internas bem uteis, como @@ -86,7 +86,7 @@ read Nome # Note que nós não precisamos declarar a variável echo Ola, $Nome # Nós temos a estrutura if normal: -# use 'man test' para mais infomações para as condicionais +# use 'man test' para mais informações para as condicionais if [ $Nome -ne $USER ] then echo "Seu nome não é o seu username" @@ -109,7 +109,7 @@ then echo "Isso vai rodar se $Nome é Daniela ou Jose." fi -# Expressões são denotadas com o seguinte formato +# Expressões são escritas com o seguinte formato echo $(( 10 + 5)) # Diferentemente das outras linguagens de programação, bash é um shell, então ele @@ -118,9 +118,9 @@ echo $(( 10 + 5)) ls #Esse comando tem opções que controlam sua execução -ls -l # Lista todo arquivo e diretorio em linhas separadas +ls -l # Lista todo arquivo e diretório em linhas separadas -# Os resultados do comando anterior pode ser passado para outro comando como input. +# Os resultados do comando anterior podem ser passados para outro comando como input. # O comando grep filtra o input com o padrão passado. É assim que listamos apenas # os arquivos .txt no diretório atual: ls -l | grep "\.txt" @@ -241,7 +241,7 @@ head -n 10 arquivo.txt sort arquivo.txt # reporta ou omite as linhas repetidas, com -d você as reporta uniq -d arquivo.txt -# exibe apenas a primeira coluna após o caráctere ',' +# exibe apenas a primeira coluna após o caractere ',' cut -d ',' -f 1 arquivo.txt # substitui todas as ocorrencias de 'okay' por 'legal' em arquivo.txt (é compativel com regex) sed -i 's/okay/legal/g' file.txt diff --git a/pt-br/csharp-pt.html.markdown b/pt-br/csharp-pt.html.markdown index 2ff59296..384ca325 100644 --- a/pt-br/csharp-pt.html.markdown +++ b/pt-br/csharp-pt.html.markdown @@ -78,15 +78,17 @@ namespace Learning.CSharp short fooShort = 10000; ushort fooUshort = 10000; - // Integer - 32-bit integer + // Integer - inteiro de 32 bits int fooInt = 1; // (-2,147,483,648 <= int <= 2,147,483,647) uint fooUint = 1; // (0 <= uint <= 4,294,967,295) - + //Números por padrão são int ou uint, dependendo do tamanho. + // Long - 64-bit integer long fooLong = 100000L; // (-9,223,372,036,854,775,808 <= long <= 9,223,372,036,854,775,807) ulong fooUlong = 100000L; // (0 <= ulong <= 18,446,744,073,709,551,615) - // Numbers default to being int or uint depending on size. - // L is used to denote that this variable value is of type long or ulong + + // Números por padrão são int ou uint dependendo do tamanho. + // L é usado para denotar que o valor da variável é do tipo long ou ulong. // Double - Double-precision 64-bit IEEE 754 Floating Point double fooDouble = 123.4; // Precision: 15-16 digits @@ -308,25 +310,26 @@ on a new line! ""Wow!"", the masses cried"; } /////////////////////////////////////// - // Converting Data Types And Typecasting + // Convertendo Data Types e Typecasting /////////////////////////////////////// - // Converting data + // Convertendo dados + + // Converter String para Integer - // Convert String To Integer - // this will throw a FormatException on failure - int.Parse("123");//returns an integer version of "123" + // isso vai jogar um erro FormatException quando houver falha + int.Parse("123");//retorna uma verão em Integer da String "123" - // try parse will default to type default on failure - // in this case: 0 + // try parse vai ir por padrão para o typo default quando houver uma falha + // nesse caso: 0 int tryInt; - if (int.TryParse("123", out tryInt)) // Function is boolean + if (int.TryParse("123", out tryInt)) // Função booleana Console.WriteLine(tryInt); // 123 - // Convert Integer To String - // Convert class has a number of methods to facilitate conversions + // Converter Integer para String + // A classe Convert possuí métodos para facilitar as conversões Convert.ToString(123); - // or + // ou tryInt.ToString(); // Casting @@ -407,12 +410,12 @@ on a new line! ""Wow!"", the masses cried"; return result; } - // You can narrow down the objects that are passed in + // Você pode pode restringir os objetos que são passados public static void IterateAndPrint<T>(T toPrint) where T: IEnumerable<int> { - // We can iterate, since T is a IEnumerable + // Nos podemos iterar, desde que T seja um "IEnumerable" foreach (var item in toPrint) - // Item is an int + // Item é um inteiro Console.WriteLine(item.ToString()); } @@ -720,9 +723,9 @@ on a new line! ""Wow!"", the masses cried"; _speed -= decrement; } - // properties get/set values - // when only data needs to be accessed, consider using properties. - // properties may have either get or set, or both + // propriedade recupera e/ou atribui valores (get/set). + // quando os dados precisam apenas ser acessados, considere o uso de propriedades. + // uma propriedade pode ter "get" ou "set", ou ambos. private bool _hasTassles; // private variable public bool HasTassles // public accessor { diff --git a/pt-br/css-pt.html.markdown b/pt-br/css-pt.html.markdown index c73669d0..38937894 100644 --- a/pt-br/css-pt.html.markdown +++ b/pt-br/css-pt.html.markdown @@ -14,15 +14,15 @@ translators: lang: pt-br --- -Nos primeiros dias da web não havia elementos visuais, apenas texto puro. Mas com maior desenvolvimento de navegadores da web, páginas web totalmente visuais também se tornou comum. +No início da web não havia elementos visuais, apenas texto puro. Mas com maior desenvolvimento de navegadores da web, páginas web totalmente visuais também se tornara comum. -CSS ajuda a manter a separação entre o conteúdo (HTML) e o look-and-feel de uma página web. +CSS ajuda a manter a separação entre o conteúdo (HTML) e o visual de uma página web. CSS permite atingir diferentes elementos em uma página HTML e atribuir diferentes propriedades visuais para eles. -Este guia foi escrito para CSS2, embora CSS3 está rapidamente se tornando popular. +Este guia foi escrito para CSS2, embora CSS3 esteja rapidamente se tornando popular. -**NOTA:** Porque CSS produz resultados visuais, a fim de aprender, você precisa tentar de tudo em um playground CSS como [dabblet](http://dabblet.com/). +**NOTA:** Porque CSS produz resultados visuais, a fim de aprender, você precisa treinar em um playground CSS como [dabblet](http://dabblet.com/). O foco principal deste artigo é sobre a sintaxe e algumas dicas gerais. ```css @@ -42,7 +42,7 @@ Abaixo um elemento de exemplo: <div class='class1 class2' id='anID' attr='value' otherAttr='pt-br foo bar' /> */ -/* Você pode direciona-lo usando uma das suas classes CSS */ +/* Você pode direcioná-lo usando uma das suas classes CSS */ .class1 { } /* ou ambas as classes! */ @@ -82,9 +82,9 @@ classe div.some [attr $ = 'ue'] {} /* Você pode selecionar um elemento que é filho de outro elemento */ div.some-parent> .class-name {} -/* Ou um descendente de um outro elemento. As crianças são os descendentes diretos de - seu elemento pai, apenas um nível abaixo da árvore. Pode ser qualquer descendentes - nivelar por baixo da árvore. */ +/* Ou um descendente de um outro elemento. Os filhos são os descendentes diretos de + seu elemento pai, apenas um nível abaixo da árvore. Pode ser quaisquer descendentes + nivelados por baixo da árvore. */ div.some-parent class-name {} /* Atenção: o mesmo seletor sem espaço tem um outro significado. @@ -97,7 +97,7 @@ div.some-parent.class-name {} /* Ou qualquer irmão que o precede */ .i am-qualquer-elemento antes ~ .Este elemento {} -/* Existem alguns selectores chamado pseudo classes que podem ser usados para selecionar um +/* Existem alguns seletores chamados pseudo classes que podem ser usados para selecionar um elemento quando ele está em um determinado estado */ /* Por exemplo, quando o cursor passa sobre um elemento */ @@ -118,7 +118,7 @@ seletor:first-child {} /* Qualquer elemento que é o último filho de seu pai */ seletor:last-child {} -/* Assim como pseudo classes, pseudo elementos permitem que você estilo certas partes de um documento */ +/* Assim como pseudo classes, pseudo elementos permitem que você estilize certas partes de um documento */ /* Corresponde a um primeiro filho virtual do elemento selecionado */ seletor::before {} @@ -127,7 +127,7 @@ seletor::before {} seletor::after {} /* Nos locais apropriados, um asterisco pode ser utilizado como um curinga para selecionar todos - elemento */ + os elementos */ * {} /* */ Todos os elementos .parent * {} /* */ todos os descendentes .parent> * {} /* */ todas as crianças @@ -181,7 +181,7 @@ seletor { ## Uso -Guardar uma folha de estilo CSS com a extensão `.css`. +Salvar uma folha de estilo CSS com a extensão `.css`. ```xml <!-- Você precisa incluir o arquivo css no da sua página <head>. Isto é o diff --git a/pt-br/cypher-pt.html.markdown b/pt-br/cypher-pt.html.markdown index 9b60f771..d4400148 100644 --- a/pt-br/cypher-pt.html.markdown +++ b/pt-br/cypher-pt.html.markdown @@ -101,7 +101,7 @@ path = shortestPath( (user)-[:KNOWS*..5]-(other) ) Crie consultas --- -Create a new node +Crie um novo nó ``` CREATE (a:Person {name:"Théo Gauchoux"}) RETURN a diff --git a/pt-br/javascript-pt.html.markdown b/pt-br/javascript-pt.html.markdown index ed4a6ff3..f12d275b 100644 --- a/pt-br/javascript-pt.html.markdown +++ b/pt-br/javascript-pt.html.markdown @@ -361,7 +361,7 @@ myObj.myFunc(); // = "Olá mundo!" var myFunc = myObj.myFunc; myFunc(); // = undefined -// Inversamente, uma função pode ser atribuída a um objeto e ganhar a acesso +// Inversamente, uma função pode ser atribuída à um objeto e ganhar a acesso // através do `this`, até mesmo se ela não for chamada quando foi definida. var myOtherFunc = function(){ return this.myString.toUpperCase(); @@ -416,7 +416,7 @@ myNewObj.myNumber; // = 5 // vai olhar imediatamente para o seu prototype. // Algumas implementações em JS deixam você acessar o objeto prototype com a -// propriedade mágica `__proto__`. Enquanto isso é util para explicar +// propriedade mágica `__proto__`. Enquanto isso é útil para explicar // prototypes, não é parte de um padrão; nós vamos falar de algumas formas de // usar prototypes depois. @@ -489,7 +489,7 @@ if (0){ } // Entretanto, esses objetos encapsulados e as funções originais compartilham -// um mesmo prototype, portanto você pode adicionar funcionalidades a uma string, +// um mesmo prototype, portanto você pode adicionar funcionalidades à uma string, // por exemplo. String.prototype.firstCharacter = function(){ return this.charAt(0); diff --git a/pt-br/julia-pt.html.markdown b/pt-br/julia-pt.html.markdown index 48d97e58..11771d96 100644 --- a/pt-br/julia-pt.html.markdown +++ b/pt-br/julia-pt.html.markdown @@ -8,7 +8,7 @@ translators: lang: pt-br --- -Julia é uma linguagem homoiconic funcional focada na computação tecnica. Ao mesmo tempo que ela tem todo o poder dos homoiconic macros, funções de primeira classe, e controle de baixo nivel, Julia é tão facil para aprender e usar quanto Python. +Julia é uma linguagem homoicônica funcional focada na computação técnica. Ao mesmo tempo que ela tem todo o poder dos macros homoicônicos, funções de primeira classe, e controle de baixo nível, Julia é tão fácil para aprender e usar quanto Python. Este tutorial é baseado no Julia 0.3. diff --git a/pt-br/latex-pt.html.markdown b/pt-br/latex-pt.html.markdown index 103af28e..58586522 100644 --- a/pt-br/latex-pt.html.markdown +++ b/pt-br/latex-pt.html.markdown @@ -62,7 +62,7 @@ Svetlana Golubeva} \newpage -% Muitos artigos de pesquisa possuem um resumo, e pode-se isar comandos +% Muitos artigos de pesquisa possuem um resumo, e pode-se usar comandos % predefinidos para isso. % Isso deve aparecer em sua ordem lógica, portanto, após o topo, % mas antes das seções principais do corpo. diff --git a/pt-br/php-pt.html.markdown b/pt-br/php-pt.html.markdown index 8a1c956e..e55f1100 100644 --- a/pt-br/php-pt.html.markdown +++ b/pt-br/php-pt.html.markdown @@ -20,7 +20,7 @@ Este documento descreve PHP 5+. // Duas barras iniciam o comentário de uma linha. -# O hash (aka pound symbol) também inicia, mas // é mais comum. +# O hash (conhecido como "pound symbol") também inicia, mas // é mais comum. /* O texto envolto por barra-asterisco e asterisco-barra diff --git a/pt-br/stylus-pt.html.markdown b/pt-br/stylus-pt.html.markdown index 804fa806..40c3c02c 100755 --- a/pt-br/stylus-pt.html.markdown +++ b/pt-br/stylus-pt.html.markdown @@ -132,7 +132,7 @@ body { background-color: $primary-color } -/* Apoś compilar ficaria assim: */ +/* Após compilar ficaria assim: */ div { display: block; margin-left: auto; @@ -184,13 +184,13 @@ button /* Funções ==============================*/ -/* Funções no Stylus permitem fazer uma variedade de tarefas, como por exemplo, menipular algum dado. */ +/* Funções no Stylus permitem fazer uma variedade de tarefas, como por exemplo, manipular algum dado. */ body { background darken(#0088DD, 50%) // Escurece a cor #0088DD em 50% } -/** Criando sua própria função */ +/* Criando sua própria função */ somar(a, b) a + b @@ -221,7 +221,7 @@ for <val-name> [, <key-name>] in <expression> for $item in (1..2) /* Repete o bloco 12 vezes */ .col-{$item} - width ($item / 12) * 100% /* Calcula a largula pelo número da coluna* + width ($item / 12) * 100% /* Calcula a largura pelo número da coluna* ``` diff --git a/pt-br/typescript-pt.html.markdown b/pt-br/typescript-pt.html.markdown index 077aa2cc..6ece02ff 100644 --- a/pt-br/typescript-pt.html.markdown +++ b/pt-br/typescript-pt.html.markdown @@ -10,7 +10,7 @@ lang: pt-br Typescript é uma linguagem que visa facilitar o desenvolvimento de aplicações em grande escala escritos em JavaScript. Typescript acrescenta conceitos comuns como classes, módulos, interfaces, genéricos e (opcional) tipagem estática para JavaScript. -É um super conjunto de JavaScript: todo o código JavaScript é o código do texto dactilografado válido para que possa ser adicionados diretamente a qualquer projeto. O compilador emite typescript JavaScript. +É um super conjunto de JavaScript: todo o código JavaScript é TypeScript válido então ele pode ser adicionado diretamente a qualquer projeto. O compilador emite typescript JavaScript. Este artigo irá se concentrar apenas em texto datilografado sintaxe extra, ao contrário de [JavaScript](javascript-pt.html.markdown). @@ -22,7 +22,7 @@ var isDone: boolean = false; var lines: number = 42; var name: string = "Anders"; -// Quando é impossível saber, há o "Qualquer" tipo +// Quando é impossível saber, há o tipo "Qualquer" var notSure: any = 4; notSure = "maybe a string instead"; notSure = false; // Ok, definitivamente um boolean @@ -65,7 +65,7 @@ interface Person { move(): void; } -// Objeto que implementa a "Pessoa" Interface +// Objeto que implementa a Interface "Pessoa" // Pode ser tratado como uma pessoa desde que tem o nome e mover propriedades var p: Person = { name: "Bobby", move: () => {} }; // Os objetos que têm a propriedade opcional: diff --git a/pt-br/yaml-pt.html.markdown b/pt-br/yaml-pt.html.markdown index 0b71877e..07903325 100644 --- a/pt-br/yaml-pt.html.markdown +++ b/pt-br/yaml-pt.html.markdown @@ -11,10 +11,10 @@ lang: pt-br YAML é uma linguagem de serialização de dados projetado para ser diretamente gravável e legível por seres humanos. -É um superconjunto de JSON, com a adição de indentação e quebras de linhas sintaticamente significativas, como Python. Ao contrário de Python, entretanto, YAML não permite o caracter literal tab para identação. +É um superconjunto de JSON, com a adição de identação e quebras de linhas sintaticamente significativas, como Python. Ao contrário de Python, entretanto, YAML não permite o caracter literal tab para identação. ```yaml -# Commentários em YAML são como este. +# Comentários em YAML são como este. ################### # TIPOS ESCALARES # @@ -33,7 +33,7 @@ chave com espaco: valor porem: "Uma string, entre aspas." "Chaves podem estar entre aspas tambem.": "É útil se você quiser colocar um ':' na sua chave." -# Seqüências de várias linhas podem ser escritos como um 'bloco literal' (utilizando |), +# Seqüências de várias linhas podem ser escritas como um 'bloco literal' (utilizando |), # ou em um 'bloco compacto' (utilizando '>'). bloco_literal: | Todo esse bloco de texto será o valor da chave 'bloco_literal', @@ -76,7 +76,7 @@ um_mapa_aninhado: # também permite tipos de coleção de chaves, mas muitas linguagens de programação # vão reclamar. -# Sequências (equivalente a listas ou arrays) semelhante à isso: +# Sequências (equivalente a listas ou arrays) semelhante a isso: uma_sequencia: - Item 1 - Item 2 @@ -118,7 +118,7 @@ datetime: 2001-12-15T02: 59: 43.1Z datetime_com_espacos 2001/12/14: 21: 59: 43.10 -5 Data: 2002/12/14 -# A tag !!binary indica que a string é na verdade um base64-encoded (condificado) +# A tag !!binary indica que a string é na verdade um base64-encoded (codificado) # representação de um blob binário. gif_file: !!binary | R0lGODlhDAAMAIQAAP//9/X17unp5WZmZgAAAOfn515eXvPz7Y6OjuDg4J+fn5 diff --git a/raku.html.markdown b/raku.html.markdown new file mode 100644 index 00000000..4f397589 --- /dev/null +++ b/raku.html.markdown @@ -0,0 +1,2412 @@ +--- +category: language +language: Raku +filename: learnraku.raku +contributors: + - ["vendethiel", "http://github.com/vendethiel"] + - ["Samantha McVey", "https://cry.nu"] +--- + +Raku (formerly Perl 6) is a highly capable, feature-rich programming language +made for at least the next hundred years. + +The primary Raku compiler is called [Rakudo](http://rakudo.org), which runs on +the JVM and the [MoarVM](http://moarvm.com). + +Meta-note: + +* Although the pound sign (`#`) is used for sentences and notes, Pod-styled + comments (more below about them) are used whenever it's convenient. +* `# OUTPUT:` is used to represent the output of a command to any standard + stream. If the output has a newline, it's represented by the `` symbol. + The output is always enclosed by angle brackets (`«` and `»`). +* `#=>` represents the value of an expression, return value of a sub, etc. + In some cases, the value is accompanied by a comment. +* Backticks are used to distinguish and highlight the language constructs + from the text. + +```perl6 +#################################################### +# 0. Comments +#################################################### + +# Single line comments start with a pound sign. + +#`( Multiline comments use #` and a quoting construct. + (), [], {}, 「」, etc, will work. +) + +=for comment +Use the same syntax for multiline comments to embed comments. +for #`(each element in) @array { + put #`(or print element) $_ #`(with newline); +} + +# You can also use Pod-styled comments. For example: + +=comment This is a comment that extends until an empty +newline is found. + +=comment +The comment doesn't need to start in the same line as the directive. + +=begin comment +This comment is multiline. + +Empty newlines can exist here too! +=end comment + +#################################################### +# 1. Variables +#################################################### + +# In Raku, you declare a lexical variable using the `my` keyword: +my $variable; + +# Raku has 3 basic types of variables: scalars, arrays, and hashes. + +# +# 1.1 Scalars +# + +# Scalars represent a single value. They start with the `$` sigil: +my $str = 'String'; + +# Double quotes allow for interpolation (which we'll see later): +my $str2 = "$str"; + +# Variable names can contain but not end with simple quotes and dashes, +# and can contain (and end with) underscores: +my $person's-belongings = 'towel'; # this works! + +my $bool = True; # `True` and `False` are Raku's boolean values. +my $inverse = !$bool; # Invert a bool with the prefix `!` operator. +my $forced-bool = so $str; # And you can use the prefix `so` operator +$forced-bool = ?$str; # to turn its operand into a Bool. Or use `?`. + +# +# 1.2 Arrays and Lists +# + +# Arrays represent multiple values. An array variable starts with the `@` +# sigil. Unlike lists, from which arrays inherit, arrays are mutable. + +my @array = 'a', 'b', 'c'; +# equivalent to: +my @letters = <a b c>; +# In the previous statement, we use the quote-words (`<>`) term for array +# of words, delimited by space. Similar to perl5's qw, or Ruby's %w. + +@array = 1, 2, 4; + +# Array indices start at 0. Here the third element is being accessed. +say @array[2]; # OUTPUT: «4» + +say "Interpolate an array using []: @array[]"; +# OUTPUT: «Interpolate an array using []: 1 2 3» + +@array[0] = -1; # Assigning a new value to an array index +@array[0, 1] = 5, 6; # Assigning multiple values + +my @keys = 0, 2; +@array[@keys] = @letters; # Assignment using an array containing index values +say @array; # OUTPUT: «a 6 b» + +# +# 1.3 Hashes, or key-value Pairs. +# + +=begin comment +Hashes are pairs of keys and values. You can construct a `Pair` object +using the syntax `key => value`. Hash tables are very fast for lookup, +and are stored unordered. Keep in mind that keys get "flattened" in hash +context, and any duplicated keys are deduplicated. +=end comment +my %hash = 'a' => 1, 'b' => 2; + +# Keys get auto-quoted when the fat comman (`=>`) is used. Trailing commas are +# okay. +%hash = a => 1, b => 2, ; + +# Even though hashes are internally stored differently than arrays, +# Raku allows you to easily create a hash from an even numbered array: +%hash = <key1 value1 key2 value2>; # Or: +%hash = "key1", "value1", "key2", "value2"; + +%hash = key1 => 'value1', key2 => 'value2'; # same result as above + +# You can also use the "colon pair" syntax. This syntax is especially +# handy for named parameters that you'll see later. +%hash = :n(2), # equivalent to `n => 2` + :is-even, # equivalent to `:is-even(True)` or `is-even => True` + :!is-odd, # equivalent to `:is-odd(False)` or `is-odd => False` +; +# The `:` (as in `:is-even`) and `:!` (as `:!is-odd`) constructs are known +# as the `True` and `False` shortcuts respectively. + +=begin comment +As demonstrated in the example below, you can use {} to get the value from a key. +If it's a string without spaces, you can actually use the quote-words operator +(`<>`). Since Raku doesn't have barewords, as Perl does, `{key1}` doesn't work +though. +=end comment +say %hash{'n'}; # OUTPUT: «2», gets value associated to key 'n' +say %hash<is-even>; # OUTPUT: «True», gets value associated to key 'is-even' + +#################################################### +# 2. Subroutines +#################################################### + +# Subroutines, or functions as most other languages call them, are +# created with the `sub` keyword. +sub say-hello { say "Hello, world" } + +# You can provide (typed) arguments. If specified, the type will be checked +# at compile-time if possible, otherwise at runtime. +sub say-hello-to( Str $name ) { + say "Hello, $name !"; +} + +# A sub returns the last value of the block. Similarly, the semicolon in +# the last expression can be omitted. +sub return-value { 5 } +say return-value; # OUTPUT: «5» + +sub return-empty { } +say return-empty; # OUTPUT: «Nil» + +# Some control flow structures produce a value, for instance `if`: +sub return-if { + if True { "Truthy" } +} +say return-if; # OUTPUT: «Truthy» + +# Some don't, like `for`: +sub return-for { + for 1, 2, 3 { 'Hi' } +} +say return-for; # OUTPUT: «Nil» + +=begin comment +Positional arguments are required by default. To make them optional, use +the `?` after the parameters' names. + +In the following example, the sub `with-optional` returns `(Any)` (Perl's +null-like value) if no argument is passed. Otherwise, it returns its argument. +=end comment +sub with-optional( $arg? ) { + $arg; +} +with-optional; # returns Any +with-optional(); # returns Any +with-optional(1); # returns 1 + +=begin comment +You can also give provide a default value when they're not passed. Doing +this make said parameter optional. Required parameters must come before +optional ones. + +In the sub `greeting`, the parameter `$type` is optional. +=end comment +sub greeting( $name, $type = "Hello" ) { + say "$type, $name!"; +} + +greeting("Althea"); # OUTPUT: «Hello, Althea!» +greeting("Arthur", "Good morning"); # OUTPUT: «Good morning, Arthur!» + +=begin comment +You can also, by using a syntax akin to the one of hashes (yay unified syntax!), +declared named parameters and thus pass named arguments to a subroutine. +By default, named parameter are optional and will default to `Any`. +=end comment +sub with-named( $normal-arg, :$named ) { + say $normal-arg + $named; +} +with-named(1, named => 6); # OUTPUT: «7» + +=begin comment +There's one gotcha to be aware of, here: If you quote your key, Raku +won't be able to see it at compile time, and you'll have a single `Pair` +object as a positional parameter, which means the function subroutine +`with-named(1, 'named' => 6);` fails. +=end comment +with-named(2, :named(5)); # OUTPUT: «7» + +# Similar to positional parameters, you can provide your named arguments with +# default values. +sub named-def( :$def = 5 ) { + say $def; +} +named-def; # OUTPUT: «5» +named-def(def => 15); # OUTPUT: «15» + +=begin comment +In order to make a named parameter mandatory, you can append `!` to the +parameter. This is the inverse of `?`, which makes a required parameter +optional. +=end comment + +sub with-mandatory-named( :$str! ) { + say "$str!"; +} +with-mandatory-named(str => "My String"); # OUTPUT: «My String!» +# with-mandatory-named; # runtime error: "Required named parameter not passed" +# with-mandatory-named(3);# runtime error: "Too many positional parameters passed" + +=begin comment +If a sub takes a named boolean argument, you can use the same "short boolean" +hash syntax we discussed earlier. +=end comment +sub takes-a-bool( $name, :$bool ) { + say "$name takes $bool"; +} +takes-a-bool('config', :bool); # OUTPUT: «config takes True» +takes-a-bool('config', :!bool); # OUTPUT: «config takes False» + +=begin comment +Since paranthesis can be omitted when calling a subroutine, you need to use +`&` in order to distinguish between a call to a sub with no arguments and +the code object. + +For instance, in this example we must use `&` to store the sub `say-hello` +(i.e., the sub's code object) in a variable, not a subroutine call. +=end comment +my &s = &say-hello; +my &other-s = sub { say "Anonymous function!" } + +=begin comment +A sub can have a "slurpy" parameter, or what one'd call a +"doesn't-matter-how-many" parameter. This is Raku's way of supporting variadic +functions. For this, you must use `*@` (slurpy) which will "take everything +else". You can have as many parameters *before* a slurpy one, but not *after*. +=end comment +sub as-many($head, *@rest) { + @rest.join(' / ') ~ " !"; +} +say as-many('Happy', 'Happy', 'Birthday'); # OUTPUT: «Happy / Birthday !» +say 'Happy', ['Happy', 'Birthday'], 'Day'; # OUTPUT: «Happy / Birthday / Day !» + +# Note that the splat (the *) did not consume the parameter before it. + +=begin comment +There are other two variations of slurpy parameters in Raku. The previous one +(namely, `*@`), known as flattened slurpy, flattens passed arguments. The other +two are `**@` and `+@` known as unflattened slurpy and "single argument rule" +slurpy respectively. The unflattened slurpy doesn't flatten its listy +arguments (or Iterable ones). +=end comment +sub b(**@arr) { @arr.perl.say }; +b(['a', 'b', 'c']); # OUTPUT: «[["a", "b", "c"],]» +b(1, $('d', 'e', 'f'), [2, 3]); # OUTPUT: «[1, ("d", "e", "f"), [2, 3]]» +b(1, [1, 2], ([3, 4], 5)); # OUTPUT: «[1, [1, 2], ([3, 4], 5)]» + +=begin comment +On the other hand, the "single argument rule" slurpy follows the "single argument +rule" which dictates how to handle the slurpy argument based upon context and +roughly states that if only a single argument is passed and that argument is +Iterable, that argument is used to fill the slurpy parameter array. In any +other case, `+@` works like `**@`. +=end comment +sub c(+@arr) { @arr.perl.say }; +c(['a', 'b', 'c']); # OUTPUT: «["a", "b", "c"]» +c(1, $('d', 'e', 'f'), [2, 3]); # OUTPUT: «[1, ("d", "e", "f"), [2, 3]]» +c(1, [1, 2], ([3, 4], 5)); # OUTPUT: «[1, [1, 2], ([3, 4], 5)]» + +=begin comment +You can call a function with an array using the "argument list flattening" +operator `|` (it's not actually the only role of this operator, +but it's one of them). +=end comment +sub concat3($a, $b, $c) { + say "$a, $b, $c"; +} +concat3(|@array); # OUTPUT: «a, b, c» + # `@array` got "flattened" as a part of the argument list + +#################################################### +# 3. Containers +#################################################### + +=begin comment +In Raku, values are actually stored in "containers". The assignment +operator asks the container on the left to store the value on its right. +When passed around, containers are marked as immutable which means that, +in a function, you'll get an error if you try to mutate one of your +arguments. If you really need to, you can ask for a mutable container by +using the `is rw` trait. +=end comment +sub mutate( $n is rw ) { + $n++; # postfix ++ operator increments its argument but returns its old value +} +my $m = 42; +mutate $m; #=> 42, the value is incremented but the old value is returned +say $m; # OUTPUT: «43» + +=begin comment +This works because we are passing the container $m to the `mutate` sub. +If we try to just pass a number instead of passing a variable, it won't work +because there is no container being passed and integers are immutable by +themselves: + +mutate 42; # Parameter '$n' expected a writable container, but got Int value +=end comment + +=begin comment +Similar error would be obtained, if a bound variable is passed to +to the subroutine. In Raku, you bind a value to a variable using the binding +operator `:=`. +=end comment +my $v := 50; # binding 50 to the variable $v +# mutate $v; # Parameter '$n' expected a writable container, but got Int value + +=begin comment +If what you want is a copy instead, use the `is copy` trait which will +cause the argument to be copied and allow you to modify the argument +inside the routine without modifying the passed argument. + +A sub itself returns a container, which means it can be marked as `rw`. +Alternatively, you can explicitly mark the returned container as mutable +by using `return-rw` instead of `return`. +=end comment +my $x = 42; +my $y = 45; +sub x-store is rw { $x } +sub y-store { return-rw $y } + +# In this case, the parentheses are mandatory or else Raku thinks that +# `x-store` and `y-store` are identifiers. +x-store() = 52; +y-store() *= 2; + +say $x; # OUTPUT: «52» +say $y; # OUTPUT: «90» + +#################################################### +# 4.Control Flow Structures +#################################################### + +# +# 4.1 if/if-else/if-elsif-else/unless +# + +=begin comment +Before talking about `if`, we need to know which values are "truthy" +(represent `True`), and which are "falsey" (represent `False`). Only these +values are falsey: 0, (), {}, "", Nil, a type (like `Str`, `Int`, etc.) and +of course, `False` itself. Any other value is truthy. +=end comment +my $number = 5; +if $number < 5 { + say "Number is less than 5" +} +elsif $number == 5 { + say "Number is equal to 5" +} +else { + say "Number is greater than 5" +} + +unless False { + say "It's not false!"; +} + +# `unless` is the equivalent of `if not (X)` which inverts the sense of a +# conditional statement. However, you cannot use `else` or `elsif` with it. + +# As you can see, you don't need parentheses around conditions. However, you +# do need the curly braces around the "body" block. For example, +# `if (True) say 'It's true';` doesn't work. + +# You can also use their statement modifier (postfix) versions: +say "Quite truthy" if True; # OUTPUT: «Quite truthy» +say "Quite falsey" unless False; # OUTPUT: «Quite falsey» + +=begin comment +The ternary operator (`??..!!`) is structured as follows `condition ?? +expression1 !! expression2` and it returns expression1 if the condition is +true. Otherwise, it returns expression2. +=end comment +my $age = 30; +say $age > 18 ?? "You are an adult" !! "You are under 18"; +# OUTPUT: «You are an adult» + +# +# 4.2 with/with-else/with-orwith-else/without +# + +=begin comment +The `with` statement is like `if`, but it tests for definedness rather than +truth, and it topicalizes on the condition, much like `given` which will +be discussed later. +=end comment +my $s = "raku"; +with $s.index("r") { say "Found a at $_" } +orwith $s.index("k") { say "Found c at $_" } +else { say "Didn't find r or k" } + +# Similar to `unless` that checks un-truthiness, you can use `without` to +# check for undefined-ness. +my $input01; +without $input01 { + say "No input given." +} +# OUTPUT: «No input given.» + +# There are also statement modifier versions for both `with` and `without`. +my $input02 = 'Hello'; +say $input02 with $input02; # OUTPUT: «Hello» +say "No input given." without $input02; + +# +# 4.3 given/when, or Raku's switch construct +# + +=begin comment +`given...when` looks like other languages' `switch`, but is much more +powerful thanks to smart matching and Raku's "topic variable", `$_`. + +The topic variable `$_ `contains the default argument of a block, a loop's +current iteration (unless explicitly named), etc. + +`given` simply puts its argument into `$_` (like a block would do), + and `when` compares it using the "smart matching" (`~~`) operator. + +Since other Raku constructs use this variable (as said before, like `for`, +blocks, `with` statement etc), this means the powerful `when` is not only +applicable along with a `given`, but instead anywhere a `$_` exists. +=end comment + +given "foo bar" { + say $_; # OUTPUT: «foo bar» + + # Don't worry about smart matching yet. Just know `when` uses it. This is + # equivalent to `if $_ ~~ /foo/`. + when /foo/ { + say "Yay !"; + } + + # smart matching anything with `True` is `True`, i.e. (`$a ~~ True`) + # so you can also put "normal" conditionals. For example, this `when` is + # equivalent to this `if`: `if $_ ~~ ($_.chars > 50) {...}` + # which means: `if $_.chars > 50 {...}` + when $_.chars > 50 { + say "Quite a long string !"; + } + + # same as `when *` (using the Whatever Star) + default { + say "Something else" + } +} + +# +# 4.4 Looping constructs +# + +# The `loop` construct is an infinite loop if you don't pass it arguments, but +# can also be a C-style `for` loop: +loop { + say "This is an infinite loop !"; + last; +} +# In the previous example, `last` breaks out of the loop very much +# like the `break` keyword in other languages. + +# The `next` keyword skips to the next iteration, like `continue` in other +# languages. Note that you can also use postfix conditionals, loops, etc. +loop (my $i = 0; $i < 5; $i++) { + next if $i == 3; + say "This is a C-style for loop!"; +} + +# The `for` constructs iterates over a list of elements. +my @odd-array = 1, 3, 5, 7, 9; + +# Accessing the array's elements with the topic variable $_. +for @odd-array { + say "I've got $_ !"; +} + +# Accessing the array's elements with a "pointy block", `->`. +# Here each element is read-only. +for @odd-array -> $variable { + say "I've got $variable !"; +} + +# Accessing the array's elements with a "doubly pointy block", `<->`. +# Here each element is read-write so mutating `$variable` mutates +# that element in the array. +for @odd-array <-> $variable { + say "I've got $variable !"; +} + +# As we saw with `given`, a `for` loop's default "current iteration" variable +# is `$_`. That means you can use `when` in a `for`loop just like you were +# able to in a `given`. +for @odd-array { + say "I've got $_"; + + # This is also allowed. A dot call with no "topic" (receiver) is sent to + # `$_` (topic variable) by default. + .say; + + # This is equivalent to the above statement. + $_.say; +} + +for @odd-array { + # You can... + next if $_ == 3; # Skip to the next iteration (`continue` in C-like lang.) + redo if $_ == 4; # Re-do iteration, keeping the same topic variable (`$_`) + last if $_ == 5; # Or break out of loop (like `break` in C-like lang.) +} + +# The "pointy block" syntax isn't specific to the `for` loop. It's just a way +# to express a block in Raku. +sub long-computation { "Finding factors of large primes" } +if long-computation() -> $result { + say "The result is $result."; +} + +#################################################### +# 5. Operators +#################################################### + +=begin comment +Since Perl languages are very much operator-based languages, Raku +operators are actually just funny-looking subroutines, in syntactic +categories, like infix:<+> (addition) or prefix:<!> (bool not). + +The categories are: + - "prefix": before (like `!` in `!True`). + - "postfix": after (like `++` in `$a++`). + - "infix": in between (like `*` in `4 * 3`). + - "circumfix": around (like `[`-`]` in `[1, 2]`). + - "post-circumfix": around, after another term (like `{`-`}` in + `%hash{'key'}`) + +The associativity and precedence list are explained below. + +Alright, you're set to go! +=end comment + +# +# 5.1 Equality Checking +# + +# `==` is numeric comparison +say 3 == 4; # OUTPUT: «False» +say 3 != 4; # OUTPUT: «True» + +# `eq` is string comparison +say 'a' eq 'b'; # OUTPUT: «False» +say 'a' ne 'b'; # OUTPUT: «True», not equal +say 'a' !eq 'b'; # OUTPUT: «True», same as above + +# `eqv` is canonical equivalence (or "deep equality") +say (1, 2) eqv (1, 3); # OUTPUT: «False» +say (1, 2) eqv (1, 2); # OUTPUT: «True» +say Int === Int; # OUTPUT: «True» + +# `~~` is the smart match operator which aliases the left hand side to $_ and +# then evaluates the right hand side. +# Here are some common comparison semantics: + +# String or numeric equality +say 'Foo' ~~ 'Foo'; # OUTPU: «True», if strings are equal. +say 12.5 ~~ 12.50; # OUTPU: «True», if numbers are equal. + +# Regex - For matching a regular expression against the left side. +# Returns a `Match` object, which evaluates as True if regexp matches. +my $obj = 'abc' ~~ /a/; +say $obj; # OUTPUT: «｢a｣» +say $obj.WHAT; # OUTPUT: «(Match)» + +# Hashes +say 'key' ~~ %hash; # OUTPUT:«True», if key exists in hash. + +# Type - Checks if left side "is of type" (can check superclasses and roles). +say 1 ~~ Int; # OUTPUT: «True» + +# Smart-matching against a boolean always returns that boolean (and will warn). +say 1 ~~ True; # OUTPUT: «True», smartmatch against True always matches +say False.so ~~ True; # OUTPUT: «True», use .so for truthiness + +# General syntax is `$arg ~~ &bool-returning-function;`. For a complete list +# of combinations, refer to the table at: +# https://docs.raku.org/language/operators#index-entry-smartmatch_operator + +# Of course, you also use `<`, `<=`, `>`, `>=` for numeric comparison. +# Their string equivalent are also available: `lt`, `le`, `gt`, `ge`. +say 3 > 4; # OUTPUT: «False» +say 3 >= 4; # OUTPUT: «False» +say 3 < 4; # OUTPUT: «True» +say 3 <= 4; # OUTPUT: «True» +say 'a' gt 'b'; # OUTPUT: «False» +say 'a' ge 'b'; # OUTPUT: «False» +say 'a' lt 'b'; # OUTPUT: «True» +say 'a' le 'b'; # OUTPUT: «True» + +# +# 5.2 Range constructor +# + +say 3 .. 7; # OUTPUT: «3..7», both included. +say 3 ..^ 7; # OUTPUT: «3..^7», exclude right endpoint. +say 3 ^.. 7; # OUTPUT: «3^..7», exclude left endpoint. +say 3 ^..^ 7; # OUTPUT: «3^..^7», exclude both endpoints. + +# The range 3 ^.. 7 is similar like 4 .. 7 when we only consider integers. +# But when we consider decimals: + +say 3.5 ~~ 4 .. 7; # OUTPUT: «False» +say 3.5 ~~ 3 ^.. 7; # OUTPUT: «True», + +# This is because the range `3 ^.. 7` only excludes anything strictly +# equal to 3. Hence, it contains decimals greater than 3. This could +# mathematically be described as 3.5 ∈ (3,7] or in set notation, +# 3.5 ∈ { x | 3 < x ≤ 7 }. + +say 3 ^.. 7 ~~ 4 .. 7; # OUTPUT: «False» + +# This also works as a shortcut for `0..^N`: +say ^10; # OUTPUT: «^10», which means 0..^10 + +# This also allows us to demonstrate that Raku has lazy/infinite arrays, +# using the Whatever Star: +my @natural = 1..*; # 1 to Infinite! Equivalent to `1..Inf`. + +# You can pass ranges as subscripts and it'll return an array of results. +say @natural[^10]; # OUTPUT: «1 2 3 4 5 6 7 8 9 10», doesn't run out of memory! + +=begin comment +NOTE: when reading an infinite list, Raku will "reify" the elements +it needs, then keep them in memory. They won't be calculated more than once. +It also will never calculate more elements that are needed. +=end comment + +# An array subscript can also be a closure. It'll be called with the array's +# length as the argument. The following two examples are equivalent: +say join(' ', @array[15..*]); # OUTPUT: «15 16 17 18 19» +say join(' ', @array[-> $n { 15..$n }]); # OUTPUT: «15 16 17 18 19» + +# NOTE: if you try to do either of those with an infinite array, you'll +# trigger an infinite loop (your program won't finish). + +# You can use that in most places you'd expect, even when assigning to an array: +my @numbers = ^20; + +# Here the numbers increase by 6, like an arithmetic sequence; more on the +# sequence (`...`) operator later. +my @seq = 3, 9 ... * > 95; # 3 9 15 21 27 [...] 81 87 93 99; + +# In this example, even though the sequence is infinite, only the 15 +# needed values will be calculated. +@numbers[5..*] = 3, 9 ... *; +say @numbers; # OUTPUT: «0 1 2 3 4 3 9 15 21 [...] 81 87», only 20 values + +# +# 5.3 and (&&), or (||) +# + +# Here `and` calls `.Bool` on both 3 and 4 and gets `True` so it returns +# 4 since both are `True`. +say (3 and 4); # OUTPUT: «4», which is truthy. +say (3 and 0); # OUTPUT: «0» +say (0 and 4); # OUTPUT: «0» + +# Here `or` calls `.Bool` on `0` and `False` which are both `False` +# so it returns `False` since both are `False`. +say (0 or False); # OUTPUT: «False». + +# Both `and` and `or` have tighter versions which also shortcut circuits. +# They're `&&` and `||` respectively. + +# `&&` returns the first operand that evaluates to `False`. Otherwise, +# it returns the last operand. +my ($a, $b, $c, $d, $e) = 1, 0, False, True, 'pi'; +say $a && $b && $c; # OUTPUT: «0», the first falsey value +say $a && $b && $c; # OUTPUT: «False», the first falsey value +say $a && $d && $e; # OUTPUT: «pi», last operand since everthing before is truthy + +# `||` returns the first argument that evaluates to `True`. +say $b || $a || $d; # OUTPUT: «1» +say $e || $d || $a; # OUTPUT: «pi» + +# And because you're going to want them, you also have compound assignment +# operators: +$a *= 2; # multiply and assignment. Equivalent to $a = $a * 2; +$b %%= 5; # divisible by and assignment. Equivalent to $b = $b %% 2; +$c div= 3; # return divisor and assignment. Equivalent to $c = $c div 3; +$d mod= 4; # return remainder and assignment. Equivalent to $d = $d mod 4; +@array .= sort; # calls the `sort` method and assigns the result back + +#################################################### +# 6. More on subs! +#################################################### + +# As we said before, Raku has *really* powerful subs. We're going +# to see a few more key concepts that make them better than in any +# other language :-). + +# +# 6.1 Unpacking! +# + +# Unpacking is the ability to "extract" arrays and keys +# (AKA "destructuring"). It'll work in `my`s and in parameter lists. +my ($f, $g) = 1, 2; +say $f; # OUTPUT: «1» +my ($, $, $h) = 1, 2, 3; # keep the non-interesting values anonymous (`$`) +say $h; # OUTPUT: «3» + +my ($head, *@tail) = 1, 2, 3; # Yes, it's the same as with "slurpy subs" +my (*@small) = 1; + +sub unpack_array( @array [$fst, $snd] ) { + say "My first is $fst, my second is $snd! All in all, I'm @array[]."; + # (^ remember the `[]` to interpolate the array) +} +unpack_array(@tail); +# OUTPUT: «My first is 3, my second is 3! All in all, I'm 2 3.» + +# If you're not using the array itself, you can also keep it anonymous, +# much like a scalar: +sub first-of-array( @ [$fst] ) { $fst } +first-of-array(@small); #=> 1 + +# However calling `first-of-array(@tail);` will throw an error ("Too many +# positional parameters passed"), which means the `@tail` has too many +# elements. + +# You can also use a slurpy parameter. You could keep `*@rest` anonymous +# Here, `@rest` is `(3,)`, since `$fst` holds the `2`. This results +# since the length (.elems) of `@rest` is 1. +sub slurp-in-array(@ [$fst, *@rest]) { + say $fst + @rest.elems; +} +slurp-in-array(@tail); # OUTPUT: «3» + +# You could even extract on a slurpy (but it's pretty useless ;-).) +sub fst(*@ [$fst]) { # or simply: `sub fst($fst) { ... }` + say $fst; +} +fst(1); # OUTPUT: «1» + +# Calling `fst(1, 2);` will throw an error ("Too many positional parameters +# passed") though. After all, the `fst` sub declares only a single positional +# parameter. + +=begin comment +You can also destructure hashes (and classes, which you'll learn about later). +The syntax is basically the same as +`%hash-name (:key($variable-to-store-value-in))`. +The hash can stay anonymous if you only need the values you extracted. + +In order to call the function, you must supply a hash wither created with +curly braces or with `%()` (recommended). Alternatively, you can pass +a variable that contains a hash. +=end comment + +sub key-of( % (:value($val), :qua($qua)) ) { + say "Got value $val, $qua time" ~~ + $qua == 1 ?? '' !! 's'; +} + +my %foo-once = %(value => 'foo', qua => 1); +key-of({value => 'foo', qua => 2}); # OUTPUT: «Got val foo, 2 times.» +key-of(%(value => 'foo', qua => 0)); # OUTPUT: «Got val foo, 0 times.» +key-of(%foo-once); # OUTPUT: «Got val foo, 1 time.» + +# The last expression of a sub is returned automatically (though you may +# indicate explicitly by using the `return` keyword, of course): +sub next-index( $n ) { + $n + 1; +} +my $new-n = next-index(3); # $new-n is now 4 + +=begin comment +This is true for everything, except for the looping constructs (due to +performance reasons): there's no reason to build a list if we're just going to +discard all the results. If you still want to build one, you can use the +`do` statement prefix or the `gather` prefix, which we'll see later: +=end comment + +sub list-of( $n ) { + do for ^$n { $_ } +} +my @list3 = list-of(3); #=> (0, 1, 2) + +# +# 6.2 Lambdas (or anonymous subroutines) +# + +# You can create a lambda by using a pointy block (`-> {}`), a +# block (`{}`) or creating a `sub` without a name. + +my &lambda1 = -> $argument { + "The argument passed to this lambda is $argument" +} + +my &lambda2 = { + "The argument passed to this lambda is $_" +} + +my &lambda3 = sub ($argument) { + "The argument passed to this lambda is $argument" +} + +=begin comment +Both pointy blocks and blocks are pretty much the same thing, except that +the former can take arguments, and that the latter can be mistaken as +a hash by the parser. That being said, blocks can declare what's known +as placeholders parameters through the twigils `$^` (for positional +parameters) and `$:` (for named parameters). More on them latern on. +=end comment + +my &mult = { $^numbers * $:times } +say mult 4, :times(6); #=> «24» + +# Both pointy blocks and blocks are quite versatile when working with functions +# that accepts other functions such as `map`, `grep`, etc. For example, +# we add 3 to each value of an array using the `map` function with a lambda: +my @nums = 1..4; +my @res1 = map -> $v { $v + 3 }, @nums; # pointy block, explicit parameter +my @res2 = map { $_ + 3 }, @nums; # block using an implicit parameter +my @res3 = map { $^val + 3 }, @nums; # block with placeholder parameter + +=begin comment +A sub (`sub {}`) has different semantics than a block (`{}` or `-> {}`): +A block doesn't have a "function context" (though it can have arguments), +which means that if you return from it, you're going to return from the +parent function. +=end comment + +# Compare: +sub is-in( @array, $elem ) { + say map({ return True if $_ == $elem }, @array); + say 'Hi'; +} + +# with: +sub truthy-array( @array ) { + say map sub ($i) { $i ?? return True !! return False }, @array; + say 'Hi'; +} + +=begin comment +In the `is-in` sub, the block will `return` out of the `is-in` sub once the +condition evaluates to `True`, the loop won't be run anymore and the +following statement won't be executed. The last statement is only executed +if the block never returns. + +On the contrary, the `truthy-array` sub will produce an array of `True` and +`False`, which will printed, and always execute the last execute statement. +Thus, the `return` only returns from the anonymous `sub` +=end comment + +=begin comment +The `anon` declarator can be used to create an anonymous sub from a +regular subroutine. The regular sub knows its name but its symbol is +prevented from getting installed in the lexical scope, the method table +and everywhere else. +=end comment +my $anon-sum = anon sub summation(*@a) { [+] @a } +say $anon-sum.name; # OUTPUT: «summation» +say $anon-sum(2, 3, 5); # OUTPUT: «10» +#say summation; # Error: Undeclared routine: ... + +# You can also use the Whatever Star to create an anonymous subroutine. +# (it'll stop at the furthest operator in the current expression). +# The following is the same as `{$_ + 3 }`, `-> { $a + 3 }`, +# `sub ($a) { $a + 3 }`, or even `{$^a + 3}` (more on this later). +my @arrayplus3v0 = map * + 3, @nums; + +# The following is the same as `-> $a, $b { $a + $b + 3 }`, +# `sub ($a, $b) { $a + $b + 3 }`, or `{ $^a + $^b + 3 }` (more on this later). +my @arrayplus3v1 = map * + * + 3, @nums; + +say (*/2)(4); # OUTPUT: «2», immediately execute the Whatever function created. +say ((*+3)/5)(5); # OUTPUT: «1.6», it works even in parens! + +# But if you need to have more than one argument (`$_`) in a block (without +# wanting to resort to `-> {}`), you can also either `$^` and `$:` which +# declared placeholder parameters or self-declared positional/named parameters. +say map { $^a + $^b + 3 }, @nums; + +# which is equivalent to the following which uses a `sub`: +map sub ($a, $b) { $a + $b + 3 }, @nums; + +# Placeholder parameters are sorted lexicographically so the following two +# statements are equivalent: +say sort { $^b <=> $^a }, @nums; +say sort -> $a, $b { $b <=> $a }, @nums; + +# +# 6.3 Multiple Dispatch +# + +# Raku can decide which variant of a `sub` to call based on the type of the +# arguments, or on arbitrary preconditions, like with a type or `where`: + +# with types: +multi sub sayit( Int $n ) { # note the `multi` keyword here + say "Number: $n"; +} +multi sayit( Str $s ) { # a multi is a `sub` by default + say "String: $s"; +} +sayit "foo"; # OUTPUT: «String: foo» +sayit 25; # OUTPUT: «Number: 25» +sayit True; # fails at *compile time* with "calling 'sayit' will never + # work with arguments of types ..." + +# with arbitrary preconditions (remember subsets?): +multi is-big(Int $n where * > 50) { "Yes!" } # using a closure +multi is-big(Int $n where {$_ > 50}) { "Yes!" } # similar to above +multi is-big(Int $ where 10..50) { "Quite." } # Using smart-matching +multi is-big(Int $) { "No" } + +subset Even of Int where * %% 2; +multi odd-or-even(Even) { "Even" } # Using the type. We don't name the argument. +multi odd-or-even($) { "Odd" } # "everything else" hence the $ variable + +# You can even dispatch based on the presence of positional and named arguments: +multi with-or-without-you($with) { + say "I wish I could but I can't"; +} +multi with-or-without-you(:$with) { + say "I can live! Actually, I can't."; +} +multi with-or-without-you { + say "Definitely can't live."; +} + +=begin comment +This is very, very useful for many purposes, like `MAIN` subs (covered +later), and even the language itself uses it in several places. + +For example, the `is` trait is actually a `multi sub` named `trait_mod:<is>`, +and it works off that. Thus, `is rw`, is simply a dispatch to a function with +this signature `sub trait_mod:<is>(Routine $r, :$rw!) {}` +=end comment + +#################################################### +# 7. About types... +#################################################### + +=begin comment +Raku is gradually typed. This means you can specify the type of your +variables/arguments/return types, or you can omit the type annotations in +in which case they'll default to `Any`. Obviously you get access to a few +base types, like `Int` and `Str`. The constructs for declaring types are +`subset`, `class`, `role`, etc. which you'll see later. + +For now, let us examine `subset` which is a "sub-type" with additional +checks. For example, "a very big integer is an `Int` that's greater than 500". +You can specify the type you're subtyping (by default, `Any`), and add +additional checks with the `where` clause. +=end comment +subset VeryBigInteger of Int where * > 500; + +# Or the set of the whole numbers: +subset WholeNumber of Int where * >= 0; +my WholeNumber $whole-six = 6; # OK +#my WholeNumber $nonwhole-one = -1; # Error: type check failed... + +# Or the set of Positive Even Numbers whose Mod 5 is 1. Notice we're +# using the previously defined WholeNumber subset. +subset PENFO of WholeNumber where { $_ %% 2 and $_ mod 5 == 1 }; +my PENFO $yes-penfo = 36; # OK +#my PENFO $no-penfo = 2; # Error: type check failed... + +#################################################### +# 8. Scoping +#################################################### + +=begin comment +In Raku, unlike many scripting languages, (such as Python, Ruby, PHP), +you must declare your variables before using them. The `my` declarator +we've used so far uses "lexical scoping". There are a few other declarators, +(`our`, `state`, ..., ) which we'll see later. This is called +"lexical scoping", where in inner blocks, you can access variables from +outer blocks. +=end comment + +my $file_scoped = 'Foo'; +sub outer { + my $outer_scoped = 'Bar'; + sub inner { + say "$file_scoped $outer_scoped"; + } + &inner; # return the function +} +outer()(); # OUTPUT: «Foo Bar» + +# As you can see, `$file_scoped` and `$outer_scoped` were captured. +# But if we were to try and use `$outer_scoped` outside the `outer` sub, +# the variable would be undefined (and you'd get a compile time error). + +#################################################### +# 9. Twigils +#################################################### + +=begin comment +There are many special `twigils` (composed sigils) in Raku. Twigils +define a variable's scope. +The `*` and `?` twigils work on standard variables: + * for dynamic variables + ? for compile-time variables + +The `!` and the `.` twigils are used with Raku's objects: + ! for attributes (instance attribute) + . for methods (not really a variable) +=end comment + +# +# `*` twigil: Dynamic Scope +# + +# These variables use the `*` twigil to mark dynamically-scoped variables. +# Dynamically-scoped variables are looked up through the caller, not through +# the outer scope. + +my $*dyn_scoped_1 = 1; +my $*dyn_scoped_2 = 10; + +sub say_dyn { + say "$*dyn_scoped_1 $*dyn_scoped_2"; +} + +sub call_say_dyn { + # Defines $*dyn_scoped_1 only for this sub. + my $*dyn_scoped_1 = 25; + + # Will change the value of the file scoped variable. + $*dyn_scoped_2 = 100; + + # $*dyn_scoped 1 and 2 will be looked for in the call. + say_dyn(); # OUTPUT: «25 100» + + # The call to `say_dyn` uses the value of $*dyn_scoped_1 from inside + # this sub's lexical scope even though the blocks aren't nested (they're + # call-nested). +} +say_dyn(); # OUTPUT: «1 10» + +# Uses $*dyn_scoped_1 as defined in `call_say_dyn` even though we are calling it +# from outside. +call_say_dyn(); # OUTPUT: «25 100» + +# We changed the value of $*dyn_scoped_2 in `call_say_dyn` so now its +# value has changed. +say_dyn(); # OUTPUT: «1 100» + +# TODO: Add information about remaining twigils + +#################################################### +# 10. Object Model +#################################################### + +=begin comment +To call a method on an object, add a dot followed by the method name: +`$object.method` + +Classes are declared with the `class` keyword. Attributes are declared +with the `has` keyword, and methods declared with the `method` keyword. + +Every attribute that is private uses the `!` twigil. For example: `$!attr`. +Immutable public attributes use the `.` twigil which creates a read-only +method named after the attribute. In fact, declaring an attribute with `.` +is equivalent to declaring the same attribute with `!` and then creating +a read-only method with the attribute's name. However, this is done for us +by Raku automatically. The easiest way to remember the `$.` twigil is +by comparing it to how methods are called. + +Raku's object model ("SixModel") is very flexible, and allows you to +dynamically add methods, change semantics, etc... Unfortunately, these will +not all be covered here, and you should refer to: +https://docs.raku.org/language/objects.html. +=end comment + +class Human { + has Str $.name; # `$.name` is immutable but with an accessor method. + has Str $.bcountry; # Use `$!bcountry` to modify it inside the class. + has Str $.ccountry is rw; # This attribute can be modified from outside. + has Int $!age = 0; # A private attribute with default value. + + method birthday { + $!age += 1; # Add a year to human's age + } + + method get-age { + return $!age; + } + + # This method is private to the class. Note the `!` before the + # method's name. + method !do-decoration { + return "$!name born in $!bcountry and now lives in $!ccountry." + } + + # This method is public, just like `birthday` and `get-age`. + method get-info { + # Invoking a method on `self` inside the class. + # Use `self!priv-method` for private method. + say self!do-decoration; + + # Use `self.public-method` for public method. + say "Age: ", self.get-age; + } +}; + +# Create a new instance of Human class. +# NOTE: Only attributes declared with the `.` twigil can be set via the +# default constructor (more later on). This constructor only accepts named +# arguments. +my $person1 = Human.new( + name => "Jord", + bcountry => "Togo", + ccountry => "Togo" +); + +# Make human 10 years old. +$person1.birthday for 1..10; + +say $person1.name; # OUTPUT: «Jord» +say $person1.bcountry; # OUTPUT: «Togo» +say $person1.ccountry; # OUTPUT: «Togo» +say $person1.get-age; # OUTPUT: «10» + +# This fails, because the `has $.bcountry`is immutable. Jord can't change +# his birthplace. +# $person1.bcountry = "Mali"; + +# This works because the `$.ccountry` is mutable (`is rw`). Now Jord's +# current country is France. +$person1.ccountry = "France"; + +# Calling methods on the instance objects. +$person1.birthday; #=> 1 +$person1.get-info; #=> Jord born in Togo and now lives in France. Age: 10 +# $person1.do-decoration; # This fails since the method `do-decoration` is private. + +# +# 10.1 Object Inheritance +# + +=begin comment +Raku also has inheritance (along with multiple inheritance). While +methods are inherited, submethods are not. Submethods are useful for +object construction and destruction tasks, such as `BUILD`, or methods that +must be overridden by subtypes. We will learn about `BUILD` later on. +=end comment + +class Parent { + has $.age; + has $.name; + + # This submethod won't be inherited by the Child class. + submethod favorite-color { + say "My favorite color is Blue"; + } + + # This method is inherited + method talk { say "Hi, my name is $!name" } +} + +# Inheritance uses the `is` keyword +class Child is Parent { + method talk { say "Goo goo ga ga" } + # This shadows Parent's `talk` method. + # This child hasn't learned to speak yet! +} + +my Parent $Richard .= new(age => 40, name => 'Richard'); +$Richard.favorite-color; # OUTPUT: «My favorite color is Blue» +$Richard.talk; # OUTPUT: «Hi, my name is Richard» +# $Richard is able to access the submethod and he knows how to say his name. + +my Child $Madison .= new(age => 1, name => 'Madison'); +$Madison.talk; # OUTPUT: «Goo goo ga ga», due to the overridden method. +# $Madison.favorite-color # does not work since it is not inherited. + +=begin comment +When you use `my T $var`, `$var` starts off with `T` itself in it, so you can +call `new` on it. (`.=` is just the dot-call and the assignment operator). +Thus, `$a .= b` is the same as `$a = $a.b`. Also note that `BUILD` (the method +called inside `new`) will set parent's properties too, so you can pass `val => +5`. +=end comment + +# +# 10.2 Roles, or Mixins +# + +# Roles are supported too (which are called Mixins in other languages) +role PrintableVal { + has $!counter = 0; + method print { + say $.val; + } +} + +# you "apply" a role (or mixin) with the `does` keyword: +class Item does PrintableVal { + has $.val; + + =begin comment + When `does`-ed, a `role` literally "mixes in" the class: + the methods and attributes are put together, which means a class + can access the private attributes/methods of its roles (but + not the inverse!): + =end comment + method access { + say $!counter++; + } + + =begin comment + However, this: method print {} is ONLY valid when `print` isn't a `multi` + with the same dispatch. This means a parent class can shadow a child class's + `multi print() {}`, but it's an error if a role does) + + NOTE: You can use a role as a class (with `is ROLE`). In this case, + methods will be shadowed, since the compiler will consider `ROLE` + to be a class. + =end comment +} + +#################################################### +# 11. Exceptions +#################################################### + +=begin comment +Exceptions are built on top of classes, in the package `X` (like `X::IO`). +In Raku, exceptions are automatically 'thrown': + +open 'foo'; # OUTPUT: «Failed to open file foo: no such file or directory» + +It will also print out what line the error was thrown at +and other error info. +=end comment + +# You can throw an exception using `die`. Here it's been commented out to +# avoid stopping the program's execution: +# die 'Error!'; # OUTPUT: «Error!» + +# Or more explicitly (commented out too): +# X::AdHoc.new(payload => 'Error!').throw; # OUTPUT: «Error!» + +=begin comment +In Raku, `orelse` is similar to the `or` operator, except it only matches +undefined variables instead of anything evaluating as `False`. +Undefined values include: `Nil`, `Mu` and `Failure` as well as `Int`, `Str` +and other types that have not been initialized to any value yet. +You can check if something is defined or not using the defined method: +=end comment +my $uninitialized; +say $uninitialized.defined; # OUTPUT: «False» + +=begin comment +When using `orelse` it will disarm the exception and alias $_ to that +failure. This will prevent it to being automatically handled and printing +lots of scary error messages to the screen. We can use the `exception` +method on the `$_` variable to access the exception +=end comment +open 'foo' orelse say "Something happened {.exception}"; + +# This also works: +open 'foo' orelse say "Something happened $_"; +# OUTPUT: «Something happened Failed to open file foo: no such file or directory» + +=begin comment +Both of those above work but in case we get an object from the left side +that is not a failure we will probably get a warning. We see below how we +can use try` and `CATCH` to be more specific with the exceptions we catch. +=end comment + +# +# 11.1 Using `try` and `CATCH` +# + +=begin comment +By using `try` and `CATCH` you can contain and handle exceptions without +disrupting the rest of the program. The `try` block will set the last +exception to the special variable `$!` (known as the error variable). +NOTE: This has no relation to $!variables seen inside class definitions. +=end comment + +try open 'foo'; +say "Well, I tried! $!" if defined $!; +# OUTPUT: «Well, I tried! Failed to open file foo: no such file or directory» + +=begin comment +Now, what if we want more control over handling the exception? +Unlike many other languages, in Raku, you put the `CATCH` block *within* +the block to `try`. Similar to how the `$_` variable was set when we +'disarmed' the exception with `orelse`, we also use `$_` in the CATCH block. +NOTE: The `$!` variable is only set *after* the `try` block has caught an +exception. By default, a `try` block has a `CATCH` block of its own that +catches any exception (`CATCH { default {} }`). +=end comment + +try { + my $a = (0 %% 0); + CATCH { + default { say "Something happened: $_" } + } +} +# OUTPUT: «Something happened: Attempt to divide by zero using infix:<%%>» + +# You can redefine it using `when`s (and `default`) to handle the exceptions +# you want to catch explicitly: + +try { + open 'foo'; + CATCH { + # In the `CATCH` block, the exception is set to the $_ variable. + when X::AdHoc { + say "Error: $_" + } + when X::Numeric::DivideByZero { + say "Error: $_"; + } + + =begin comment + Any other exceptions will be re-raised, since we don't have a `default`. + Basically, if a `when` matches (or there's a `default`), the + exception is marked as "handled" so as to prevent its re-throw + from the `CATCH` block. You still can re-throw the exception + (see below) by hand. + =end comment + default { + say "Any other error: $_" + } + } +} +# OUTPUT: «Failed to open file /dir/foo: no such file or directory» + +=begin comment +There are also some subtleties to exceptions. Some Raku subs return a +`Failure`, which is a wrapper around an `Exception` object which is +"unthrown". They're not thrown until you try to use the variables containing +them unless you call `.Bool`/`.defined` on them - then they're handled. +(the `.handled` method is `rw`, so you can mark it as `False` back yourself) +You can throw a `Failure` using `fail`. Note that if the pragma `use fatal` +is on, `fail` will throw an exception (like `die`). +=end comment + +my $value = 0/0; # We're not trying to access the value, so no problem. +try { + say 'Value: ', $value; # Trying to use the value + CATCH { + default { + say "It threw because we tried to get the fail's value!" + } + } +} + +=begin comment +There is also another kind of exception: Control exceptions. Those are "good" +exceptions, which happen when you change your program's flow, using operators +like `return`, `next` or `last`. You can "catch" those with `CONTROL` (not 100% +working in Rakudo yet). +=end comment + +#################################################### +# 12. Packages +#################################################### + +=begin comment +Packages are a way to reuse code. Packages are like "namespaces", and any +element of the six model (`module`, `role`, `class`, `grammar`, `subset` and +`enum`) are actually packages. (Packages are the lowest common denominator) +Packages are important - especially as Perl is well-known for CPAN, +the Comprehensive Perl Archive Network. +=end comment + +# You can use a module (bring its declarations into scope) with `use`: +use JSON::Tiny; # if you installed Rakudo* or Panda, you'll have this module +say from-json('[1]').perl; # OUTPUT: «[1]» + +=begin comment +You should not declare packages using the `package` keyword (unlike Perl 5). +Instead, use `class Package::Name::Here;` to declare a class, or if you only +want to export variables/subs, you can use `module` instead. +=end comment + +# If `Hello` doesn't exist yet, it'll just be a "stub", that can be redeclared +# as something else later. +module Hello::World { # bracketed form + # declarations here +} + +# The file-scoped form which extends until the end of the file. For +# instance, `unit module Parse::Text;` will extend until of the file. + +# A grammar is a package, which you could `use`. You will learn more about +# grammars in the regex section. +grammar Parse::Text::Grammar { +} + +# As said before, any part of the six model is also a package. +# Since `JSON::Tiny` uses its own `JSON::Tiny::Actions` class, you can use it: +my $actions = JSON::Tiny::Actions.new; + +# We'll see how to export variables and subs in the next part. + +#################################################### +# 13. Declarators +#################################################### + +=begin comment +In Raku, you get different behaviors based on how you declare a variable. +You've already seen `my` and `has`, we'll now explore the others. + +`our` - these declarations happen at `INIT` time -- (see "Phasers" below). +It's like `my`, but it also creates a package variable. All packagish +things such as `class`, `role`, etc. are `our` by default. +=end comment + +module Var::Increment { + # NOTE: `our`-declared variables cannot be typed. + our $our-var = 1; + my $my-var = 22; + + our sub Inc { + our sub available { # If you try to make inner `sub`s `our`... + # ... Better know what you're doing (Don't !). + say "Don't do that. Seriously. You'll get burned."; + } + + my sub unavailable { # `sub`s are `my`-declared by default + say "Can't access me from outside, I'm 'my'!"; + } + say ++$our-var; # Increment the package variable and output its value + } + +} + +say $Var::Increment::our-var; # OUTPUT: «1», this works! +say $Var::Increment::my-var; # OUTPUT: «(Any)», this will not work! + +say Var::Increment::Inc; # OUTPUT: «2» +say Var::Increment::Inc; # OUTPUT: «3», notice how the value of $our-var was retained. + +# Var::Increment::unavailable; # OUTPUT: «Could not find symbol '&unavailable'» + +# `constant` - these declarations happen at `BEGIN` time. You can use +# the `constant` keyword to declare a compile-time variable/symbol: +constant Pi = 3.14; +constant $var = 1; + +# And if you're wondering, yes, it can also contain infinite lists. +constant why-not = 5, 15 ... *; +say why-not[^5]; # OUTPUT: «5 15 25 35 45» + +# `state` - these declarations happen at run time, but only once. State +# variables are only initialized one time. In other languages such as C +# they exist as `static` variables. +sub fixed-rand { + state $val = rand; + say $val; +} +fixed-rand for ^10; # will print the same number 10 times + +# Note, however, that they exist separately in different enclosing contexts. +# If you declare a function with a `state` within a loop, it'll re-create the +# variable for each iteration of the loop. See: +for ^5 -> $a { + sub foo { + # This will be a different value for every value of `$a` + state $val = rand; + } + for ^5 -> $b { + # This will print the same value 5 times, but only 5. Next iteration + # will re-run `rand`. + say foo; + } +} + +#################################################### +# 14. Phasers +#################################################### + +=begin comment +Phasers in Raku are blocks that happen at determined points of time in +your program. They are called phasers because they mark a change in the +phase of a program. For example, when the program is compiled, a for loop +runs, you leave a block, or an exception gets thrown (The `CATCH` block is +actually a phaser!). Some of them can be used for their return values, +some of them can't (those that can have a "[*]" in the beginning of their +explanation text). Let's have a look! +=end comment + +# +# 14.1 Compile-time phasers +# +BEGIN { say "[*] Runs at compile time, as soon as possible, only once" } +CHECK { say "[*] Runs at compile time, as late as possible, only once" } + +# +# 14.2 Run-time phasers +# +INIT { say "[*] Runs at run time, as soon as possible, only once" } +END { say "Runs at run time, as late as possible, only once" } + +# +# 14.3 Block phasers +# +ENTER { say "[*] Runs everytime you enter a block, repeats on loop blocks" } +LEAVE { + say "Runs everytime you leave a block, even when an exception + happened. Repeats on loop blocks." +} + +PRE { + say "Asserts a precondition at every block entry, + before ENTER (especially useful for loops)"; + say "If this block doesn't return a truthy value, + an exception of type X::Phaser::PrePost is thrown."; +} + +# Example (commented out): +for 0..2 { + # PRE { $_ > 1 } # OUTPUT: «Precondition '{ $_ > 1 }' failed +} + +POST { + say "Asserts a postcondition at every block exit, + after LEAVE (especially useful for loops)"; + say "If this block doesn't return a truthy value, + an exception of type X::Phaser::PrePost is thrown, like PRE."; +} + +# Example (commented out): +for 0..2 { + # POST { $_ < 1 } # OUTPUT: «Postcondition '{ $_ < 1 }' failed +} + +# +# 14.4 Block/exceptions phasers +# +{ + KEEP { say "Runs when you exit a block successfully + (without throwing an exception)" } + UNDO { say "Runs when you exit a block unsuccessfully + (by throwing an exception)" } +} + +# +# 14.5 Loop phasers +# +for ^5 { + FIRST { say "[*] The first time the loop is run, before ENTER" } + NEXT { say "At loop continuation time, before LEAVE" } + LAST { say "At loop termination time, after LEAVE" } +} + +# +# 14.6 Role/class phasers +# +COMPOSE { + say "When a role is composed into a class. /!\ NOT YET IMPLEMENTED" +} + +# They allow for cute tricks or clever code...: +say "This code took " ~ (time - CHECK time) ~ "s to compile"; + +# ... or clever organization: +class DB { + method start-transaction { say "Starting transation!" } + method commit { say "Commiting transaction..." } + method rollback { say "Something went wrong. Rollingback!" } +} + +sub do-db-stuff { + my DB $db .= new; + $db.start-transaction; # start a new transaction + KEEP $db.commit; # commit the transaction if all went well + UNDO $db.rollback; # or rollback if all hell broke loose +} + +do-db-stuff(); + +#################################################### +# 15. Statement prefixes +#################################################### + +=begin comment +Those act a bit like phasers: they affect the behavior of the following +code. Though, they run in-line with the executable code, so they're in +lowercase. (`try` and `start` are theoretically in that list, but explained +elsewhere) NOTE: all of these (except start) don't need explicit curly +braces `{` and `}`. + +=end comment + +# +# 15.1 `do` - It runs a block or a statement as a term. +# + +# Normally you cannot use a statement as a value (or "term"). `do` helps +# us do it. With `do`, an `if`, for example, becomes a term returning a value. +=for comment :reason<this fails since `if` is a statement> +my $value = if True { 1 } + +# this works! +my $get-five = do if True { 5 } + +# +# 15.1 `once` - makes sure a piece of code only runs once. +# +for ^5 { + once say 1 +}; +# OUTPUT: «1», only prints ... once + +# Similar to `state`, they're cloned per-scope. +for ^5 { + sub { once say 1 }() +}; +# OUTPUT: «1 1 1 1 1», prints once per lexical scope. + +# +# 15.2 `gather` - co-routine thread. +# + +# The `gather` constructs allows us to `take` several values from an array/list, +# much like `do`. +say gather for ^5 { + take $_ * 3 - 1; + take $_ * 3 + 1; +} +# OUTPUT: «-1 1 2 4 5 7 8 10 11 13» + +say join ',', gather if False { + take 1; + take 2; + take 3; +} +# Doesn't print anything. + +# +# 15.3 `eager` - evaluates a statement eagerly (forces eager context). + +# Don't try this at home. This will probably hang for a while (and might crash) +# so commented out. +# eager 1..*; + +# But consider, this version which doesn't print anything +constant thricev0 = gather for ^3 { say take $_ }; +# to: +constant thricev1 = eager gather for ^3 { say take $_ }; # OUTPUT: «0 1 2» + +#################################################### +# 16. Iterables +#################################################### + +# Iterables are objects that can be iterated over for things such as +# the `for` construct. + +# +# 16.1 `flat` - flattens iterables. +# +say (1, 10, (20, 10) ); # OUTPUT: «(1 10 (20 10))», notice how nested + # lists are preserved +say (1, 10, (20, 10) ).flat; # OUTPUT: «(1 10 20 10)», now the iterable is flat + +# +# 16.2 `lazy` - defers actual evaluation until value is fetched by forcing lazy context. +# +my @lazy-array = (1..100).lazy; +say @lazy-array.is-lazy; # OUTPUT: «True», check for laziness with the `is-lazy` method. + +say @lazy-array; # OUTPUT: «[...]», List has not been iterated on! + +# This works and will only do as much work as is needed. +for @lazy-array { .print }; + +# (**TODO** explain that gather/take and map are all lazy) + +# +# 16.3 `sink` - an `eager` that discards the results by forcing sink context. +# +constant nilthingie = sink for ^3 { .say } #=> 0 1 2 +say nilthingie.perl; # OUTPUT: «Nil» + +# +# 16.4 `quietly` - suppresses warnings in blocks. +# +quietly { warn 'This is a warning!' }; # No output + +#################################################### +# 17. More operators thingies! +#################################################### + +# Everybody loves operators! Let's get more of them. + +# The precedence list can be found here: +# https://docs.raku.org/language/operators#Operator_Precedence +# But first, we need a little explanation about associativity: + +# +# 17.1 Binary operators +# + +my ($p, $q, $r) = (1, 2, 3); + +=begin comment +Given some binary operator § (not a Raku-supported operator), then: + +$p § $q § $r; # with a left-associative §, this is ($p § $q) § $r +$p § $q § $r; # with a right-associative §, this is $p § ($q § $r) +$p § $q § $r; # with a non-associative §, this is illegal +$p § $q § $r; # with a chain-associative §, this is ($p § $q) and ($q § $r)§ +$p § $q § $r; # with a list-associative §, this is `infix:<>` +=end comment + +# +# 17.2 Unary operators +# + +=begin comment +Given some unary operator § (not a Raku-supported operator), then: +§$p§ # with left-associative §, this is (§$p)§ +§$p§ # with right-associative §, this is §($p§) +§$p§ # with non-associative §, this is illegal +=end comment + +# +# 17.3 Create your own operators! +# + +=begin comment +Okay, you've been reading all of that, so you might want to try something +more exciting?! I'll tell you a little secret (or not-so-secret): +In Raku, all operators are actually just funny-looking subroutines. + +You can declare an operator just like you declare a sub. In the following +example, `prefix` refers to the operator categories (prefix, infix, postfix, +circumfix, and post-circumfix). +=end comment +sub prefix:<win>( $winner ) { + say "$winner Won!"; +} +win "The King"; # OUTPUT: «The King Won!» + +# you can still call the sub with its "full name": +say prefix:<!>(True); # OUTPUT: «False» +prefix:<win>("The Queen"); # OUTPUT: «The Queen Won!» + +sub postfix:<!>( Int $n ) { + [*] 2..$n; # using the reduce meta-operator... See below ;-)! +} +say 5!; # OUTPUT: «120» + +# Postfix operators ('after') have to come *directly* after the term. +# No whitespace. You can use parentheses to disambiguate, i.e. `(5!)!` + +sub infix:<times>( Int $n, Block $r ) { # infix ('between') + for ^$n { + # You need the explicit parentheses to call the function in `$r`, + # else you'd be referring at the code object itself, like with `&r`. + $r(); + } +} +3 times -> { say "hello" }; # OUTPUT: «hellohellohello» + +# It's recommended to put spaces around your infix operator calls. + +# For circumfix and post-circumfix ones +multi circumfix:<[ ]>( Int $n ) { + $n ** $n +} +say [5]; # OUTPUT: «3125» + +# Circumfix means 'around'. Again, no whitespace. + +multi postcircumfix:<{ }>( Str $s, Int $idx ) { + $s.substr($idx, 1); +} +say "abc"{1}; # OUTPUT: «b», after the term `"abc"`, and around the index (1) + +# Post-circumfix is 'after a term, around something' + +=begin comment +This really means a lot -- because everything in Raku uses this. +For example, to delete a key from a hash, you use the `:delete` adverb +(a simple named argument underneath). For instance, the following statements +are equivalent. +=end comment +my %person-stans = + 'Giorno Giovanna' => 'Gold Experience', + 'Bruno Bucciarati' => 'Sticky Fingers'; +my $key = 'Bruno Bucciarati'; +%person-stans{$key}:delete; +postcircumfix:<{ }>( %person-stans, 'Giorno Giovanna', :delete ); +# (you can call operators like this) + +=begin comment +It's *all* using the same building blocks! Syntactic categories +(prefix infix ...), named arguments (adverbs), ..., etc. used to build +the language - are available to you. Obviously, you're advised against +making an operator out of *everything* -- with great power comes great +responsibility. +=end comment + +# +# 17.4 Meta operators! +# + +=begin comment +Oh boy, get ready!. Get ready, because we're delving deep into the rabbit's +hole, and you probably won't want to go back to other languages after +reading this. (I'm guessing you don't want to go back at this point but +let's continue, for the journey is long and enjoyable!). + +Meta-operators, as their name suggests, are *composed* operators. Basically, +they're operators that act on another operators. + +The reduce meta-operator is a prefix meta-operator that takes a binary +function and one or many lists. If it doesn't get passed any argument, +it either returns a "default value" for this operator (a meaningless value) +or `Any` if there's none (examples below). Otherwise, it pops an element +from the list(s) one at a time, and applies the binary function to the last +result (or the first element of a list) and the popped element. +=end comment + +# To sum a list, you could use the reduce meta-operator with `+`, i.e.: +say [+] 1, 2, 3; # OUTPUT: «6», equivalent to (1+2)+3. + +# To multiply a list +say [*] 1..5; # OUTPUT: «120», equivalent to ((((1*2)*3)*4)*5). + +# You can reduce with any operator, not just with mathematical ones. +# For example, you could reduce with `//` to get first defined element +# of a list: +say [//] Nil, Any, False, 1, 5; # OUTPUT: «False» + # (Falsey, but still defined) +# Or with relational operators, i.e., `>` to check elements of a list +# are ordered accordingly: +say [>] 234, 156, 6, 3, -20; # OUTPUT: «True» + +# Default value examples: +say [*] (); # OUTPUT: «1», empty product +say [+] (); # OUTPUT: «0», empty sum +say [//]; # OUTPUT: «(Any)» + # There's no "default value" for `//`. + +# You can also use it with a function you made up, +# You can also surround using double brackets: +sub add($a, $b) { $a + $b } +say [[&add]] 1, 2, 3; # OUTPUT: «6» + +=begin comment +The zip meta-operator is an infix meta-operator that also can be used as a +"normal" operator. It takes an optional binary function (by default, it +just creates a pair), and will pop one value off of each array and call +its binary function on these until it runs out of elements. It returns an +array with all of these new elements. +=end comment +say (1, 2) Z (3, 4); # OUTPUT: «((1, 3), (2, 4))» +say 1..3 Z+ 4..6; # OUTPUT: «(5, 7, 9)» + +# Since `Z` is list-associative (see the list above), you can use it on more +# than one list. +(True, False) Z|| (False, False) Z|| (False, False); # (True, False) + +# And, as it turns out, you can also use the reduce meta-operator with it: +[Z||] (True, False), (False, False), (False, False); # (True, False) + +# And to end the operator list: + +=begin comment +The sequence operator (`...`) is one of Raku's most powerful features: +It's composed by the list (which might include a closure) you want Raku to +deduce from on the left and a value (or either a predicate or a Whatever Star +for a lazy infinite list) on the right that states when to stop. +=end comment + +# Basic arithmetic sequence +my @listv0 = 1, 2, 3...10; + +# This dies because Raku can't figure out the end +# my @list = 1, 3, 6...10; + +# As with ranges, you can exclude the last element (the iteration ends when +# the predicate matches). +my @listv1 = 1, 2, 3...^10; + +# You can use a predicate (with the Whatever Star). +my @listv2 = 1, 3, 9...* > 30; + +# Equivalent to the example above but using a block here. +my @listv3 = 1, 3, 9 ... { $_ > 30 }; + +# Lazy infinite list of fibonacci sequence, computed using a closure! +my @fibv0 = 1, 1, *+* ... *; + +# Equivalent to the above example but using a pointy block. +my @fibv1 = 1, 1, -> $a, $b { $a + $b } ... *; + +# Equivalent to the above example but using a block with placeholder parameters. +my @fibv2 = 1, 1, { $^a + $^b } ... *; + +=begin comment +In the examples with explicit parameters (i.e., $a and $b), $a and $b +will always take the previous values, meaning that for the Fibonacci sequence, +they'll start with $a = 1 and $b = 1 (values we set by hand), then $a = 1 +and $b = 2 (result from previous $a + $b), and so on. +=end comment + +=begin comment +# In the example we use a range as an index to access the sequence. However, +# it's worth noting that for ranges, once reified, elements aren't re-calculated. +# That's why, for instance, `@primes[^100]` will take a long time the first +# time you print it but then it will be instateneous. +=end comment +say @fibv0[^10]; # OUTPUT: «1 1 2 3 5 8 13 21 34 55» + +#################################################### +# 18. Regular Expressions +#################################################### + +=begin comment +I'm sure a lot of you have been waiting for this one. Well, now that you know +a good deal of Raku already, we can get started. First off, you'll have to +forget about "PCRE regexps" (perl-compatible regexps). + +IMPORTANT: Don't skip them because you know PCRE. They're different. Some +things are the same (like `?`, `+`, and `*`), but sometimes the semantics +change (`|`). Make sure you read carefully, because you might trip over a +new behavior. + +Raku has many features related to RegExps. After all, Rakudo parses itself. +We're first going to look at the syntax itself, then talk about grammars +(PEG-like), differences between `token`, `regex` and `rule` declarators, +and some more. Side note: you still have access to PCRE regexps using the +`:P5` modifier which we won't be discussing this in this tutorial, though. + +In essence, Raku natively implements PEG ("Parsing Expression Grammars"). +The pecking order for ambiguous parses is determined by a multi-level +tie-breaking test: + - Longest token matching: `foo\s+` beats `foo` (by 2 or more positions) + - Longest literal prefix: `food\w*` beats `foo\w*` (by 1) + - Declaration from most-derived to less derived grammars + (grammars are actually classes) + - Earliest declaration wins +=end comment +say so 'a' ~~ /a/; # OUTPUT: «True» +say so 'a' ~~ / a /; # OUTPUT: «True», more readable with some spaces! + +=begin comment +In all our examples, we're going to use the smart-matching operator against +a regexp. We're converting the result using `so` to a Boolean value because, +in fact, it's returning a `Match` object. They know how to respond to list +indexing, hash indexing, and return the matched string. The results of the +match are available in the `$/` variable (implicitly lexically-scoped). You +can also use the capture variables which start at 0: `$0`, `$1', `$2`... + +You can also note that `~~` does not perform start/end checking, meaning +the regexp can be matched with just one character of the string. We'll +explain later how you can do it. + +In Raku, you can have any alphanumeric as a literal, everything else has +to be escaped by using a backslash or quotes. +=end comment +say so 'a|b' ~~ / a '|' b /; # OUTPUT: «True», it wouldn't mean the same + # thing if `|` wasn't escaped. +say so 'a|b' ~~ / a \| b /; # OUTPUT: «True», another way to escape it. + +# The whitespace in a regex is actually not significant, unless you use the +# `:s` (`:sigspace`, significant space) adverb. +say so 'a b c' ~~ / a b c /; #=> `False`, space is not significant here! +say so 'a b c' ~~ /:s a b c /; #=> `True`, we added the modifier `:s` here. + +# If we use only one space between strings in a regex, Raku will warn us +# about space being not signicant in the regex: +say so 'a b c' ~~ / a b c /; # OUTPUT: «False» +say so 'a b c' ~~ / a b c /; # OUTPUT: «False» + +=begin comment +NOTE: Please use quotes or `:s` (`:sigspace`) modifier (or, to suppress this +warning, omit the space, or otherwise change the spacing). To fix this and make +the spaces less ambiguous, either use at least two spaces between strings +or use the `:s` adverb. +=end comment + +# As we saw before, we can embed the `:s` inside the slash delimiters, but we +# can also put it outside of them if we specify `m` for 'match': +say so 'a b c' ~~ m:s/a b c/; # OUTPUT: «True» + +# By using `m` to specify 'match', we can also use other delimiters: +say so 'abc' ~~ m{a b c}; # OUTPUT: «True» +say so 'abc' ~~ m[a b c]; # OUTPUT: «True» + +# `m/.../` is equivalent to `/.../`: +say 'raku' ~~ m/raku/; # OUTPUT: «True» +say 'raku' ~~ /raku/; # OUTPUT: «True» + +# Use the `:i` adverb to specify case insensitivity: +say so 'ABC' ~~ m:i{a b c}; # OUTPUT: «True» + +# However, whitespace is important as for how modifiers are applied +# (which you'll see just below) ... + +# +# 18.1 Quantifiers - `?`, `+`, `*` and `**`. +# + +# `?` - zero or one match +say so 'ac' ~~ / a b c /; # OUTPUT: «False» +say so 'ac' ~~ / a b? c /; # OUTPUT: «True», the "b" matched 0 times. +say so 'abc' ~~ / a b? c /; # OUTPUT: «True», the "b" matched 1 time. + +# ... As you read before, whitespace is important because it determines which +# part of the regex is the target of the modifier: +say so 'def' ~~ / a b c? /; # OUTPUT: «False», only the "c" is optional +say so 'def' ~~ / a b? c /; # OUTPUT: «False», whitespace is not significant +say so 'def' ~~ / 'abc'? /; # OUTPUT: «True», the whole "abc" group is optional + +# Here (and below) the quantifier applies only to the "b" + +# `+` - one or more matches +say so 'ac' ~~ / a b+ c /; # OUTPUT: «False», `+` wants at least one 'b' +say so 'abc' ~~ / a b+ c /; # OUTPUT: «True», one is enough +say so 'abbbbc' ~~ / a b+ c /; # OUTPUT: «True», matched 4 "b"s + +# `*` - zero or more matches +say so 'ac' ~~ / a b* c /; # OUTPU: «True», they're all optional +say so 'abc' ~~ / a b* c /; # OUTPU: «True» +say so 'abbbbc' ~~ / a b* c /; # OUTPU: «True» +say so 'aec' ~~ / a b* c /; # OUTPU: «False», "b"(s) are optional, not replaceable. + +# `**` - (Unbound) Quantifier +# If you squint hard enough, you might understand why exponentation is used +# for quantity. +say so 'abc' ~~ / a b**1 c /; # OUTPU: «True», exactly one time +say so 'abc' ~~ / a b**1..3 c /; # OUTPU: «True», one to three times +say so 'abbbc' ~~ / a b**1..3 c /; # OUTPU: «True» +say so 'abbbbbbc' ~~ / a b**1..3 c /; # OUTPU: «Fals», too much +say so 'abbbbbbc' ~~ / a b**3..* c /; # OUTPU: «True», infinite ranges are ok + +# +# 18.2 `<[]>` - Character classes +# + +# Character classes are the equivalent of PCRE's `[]` classes, but they use a +# more raku-ish syntax: +say 'fooa' ~~ / f <[ o a ]>+ /; # OUTPUT: «fooa» + +# You can use ranges (`..`): +say 'aeiou' ~~ / a <[ e..w ]> /; # OUTPUT: «ae» + +# Just like in normal regexes, if you want to use a special character, escape +# it (the last one is escaping a space which would be equivalent to using +# ' '): +say 'he-he !' ~~ / 'he-' <[ a..z \! \ ]> + /; # OUTPUT: «he-he !» + +# You'll get a warning if you put duplicate names (which has the nice effect +# of catching the raw quoting): +'he he' ~~ / <[ h e ' ' ]> /; +# Warns "Repeated character (') unexpectedly found in character class" + +# You can also negate character classes... (`<-[]>` equivalent to `[^]` in PCRE) +say so 'foo' ~~ / <-[ f o ]> + /; # OUTPUT: «False» + +# ... and compose them: +# any letter except "f" and "o" +say so 'foo' ~~ / <[ a..z ] - [ f o ]> + /; # OUTPUT: «False» + +# no letter except "f" and "o" +say so 'foo' ~~ / <-[ a..z ] + [ f o ]> + /; # OUTPUT: «True» + +# the + doesn't replace the left part +say so 'foo!' ~~ / <-[ a..z ] + [ f o ]> + /; # OUTPUT: «True» + +# +# 18.3 Grouping and capturing +# + +# Group: you can group parts of your regexp with `[]`. Unlike PCRE's `(?:)`, +# these groups are *not* captured. +say so 'abc' ~~ / a [ b ] c /; # OUTPUT: «True», the grouping does nothing +say so 'foo012012bar' ~~ / foo [ '01' <[0..9]> ] + bar /; # OUTPUT: «True» + +# The previous line returns `True`. The regex matches "012" one or more time +# (achieved by the the `+` applied to the group). + +# But this does not go far enough, because we can't actually get back what +# we matched. + +# Capture: The results of a regexp can be *captured* by using parentheses. +say so 'fooABCABCbar' ~~ / foo ( 'A' <[A..Z]> 'C' ) + bar /; # OUTPUT: «True» +# (using `so` here, see `$/` below) + +# So, starting with the grouping explanations. As we said before, our `Match` +# object is stored inside the `$/` variable: +say $/; # Will either print the matched object or `Nil` if nothing matched. + +# As we also said before, it has array indexing: +say $/[0]; # OUTPUT: «｢ABC｣ ｢ABC｣», + +# The corner brackets (｢..｣) represent (and are) `Match` objects. In the +# previous example, we have an array of them. + +say $0; # The same as above. + +=begin comment +Our capture is `$0` because it's the first and only one capture in the +regexp. You might be wondering why it's an array, and the answer is simple: +Some captures (indexed using `$0`, `$/[0]` or a named one) will be an array +if and only if they can have more than one element. Thus any capture with +`*`, `+` and `**` (whatever the operands), but not with `?`. +Let's use examples to see that: + +NOTE: We quoted A B C to demonstrate that the whitespace between them isn't +significant. If we want the whitespace to *be* significant there, we can use the +`:sigspace` modifier. +=end comment +say so 'fooABCbar' ~~ / foo ( "A" "B" "C" )? bar /; # OUTPUT: «True» +say $/[0]; # OUTPUT: «｢ABC｣» +say $0.WHAT; # OUTPUT: «(Match)» + # There can't be more than one, so it's only a single match object. + +say so 'foobar' ~~ / foo ( "A" "B" "C" )? bar /; # OUTPUT: «True» +say $0.WHAT; # OUTPUT: «(Any)», this capture did not match, so it's empty. + +say so 'foobar' ~~ / foo ( "A" "B" "C" ) ** 0..1 bar /; #=> OUTPUT: «True» +say $0.WHAT; # OUTPUT: «(Array)», A specific quantifier will always capture + # an Array, be a range or a specific value (even 1). + +# The captures are indexed per nesting. This means a group in a group will be +# nested under its parent group: `$/[0][0]`, for this code: +'hello-~-world' ~~ / ( 'hello' ( <[ \- \~ ]> + ) ) 'world' /; +say $/[0].Str; # OUTPUT: «hello~» +say $/[0][0].Str; # OUTPUT: «~» + +=begin comment +This stems from a very simple fact: `$/` does not contain strings, integers +or arrays, it only contains `Match` objects. These contain the `.list`, `.hash` +and `.Str` methods but you can also just use `match<key>` for hash access +and `match[idx]` for array access. + +In the following example, we can see `$_` is a list of `Match` objects. +Each of them contain a wealth of information: where the match started/ended, +the "ast" (see actions later), etc. You'll see named capture below with +grammars. +=end comment +say $/[0].list.perl; # OUTPUT: «(Match.new(...),).list» + +# Alternation - the `or` of regexes +# WARNING: They are DIFFERENT from PCRE regexps. +say so 'abc' ~~ / a [ b | y ] c /; # OUTPU: «True», Either "b" or "y". +say so 'ayc' ~~ / a [ b | y ] c /; # OUTPU: «True», Obviously enough... + +# The difference between this `|` and the one you're used to is +# LTM ("Longest Token Matching") strategy. This means that the engine will +# always try to match as much as possible in the string. +say 'foo' ~~ / fo | foo /; # OUTPUT: «foo», instead of `fo`, because it's longer. + +=begin comment +To decide which part is the "longest", it first splits the regex in two parts: + + * The "declarative prefix" (the part that can be statically analyzed) + which includes alternations (`|`), conjunctions (`&`), sub-rule calls (not + yet introduced), literals, characters classes and quantifiers. + + * The "procedural part" includes everything else: back-references, + code assertions, and other things that can't traditionnaly be represented + by normal regexps. + +Then, all the alternatives are tried at once, and the longest wins. +=end comment + +# Examples: +# DECLARATIVE | PROCEDURAL +/ 'foo' \d+ [ <subrule1> || <subrule2> ] /; + +# DECLARATIVE (nested groups are not a problem) +/ \s* [ \w & b ] [ c | d ] /; + +# However, closures and recursion (of named regexes) are procedural. +# There are also more complicated rules, like specificity (literals win +# over character classes). + +# NOTE: The alternation in which all the branches are tried in order +# until the first one matches still exists, but is now spelled `||`. +say 'foo' ~~ / fo || foo /; # OUTPUT: «fo», in this case. + +#################################################### +# 19. Extra: the MAIN subroutine +#################################################### + +=begin comment +The `MAIN` subroutine is called when you run a Raku file directly. It's +very powerful, because Raku actually parses the arguments and pass them +as such to the sub. It also handles named argument (`--foo`) and will even +go as far as to autogenerate a `--help` flag. +=end comment + +sub MAIN($name) { + say "Hello, $name!"; +} +=begin comment +Supposing the code above is in file named cli.raku, then running in the command +line (e.g., $ raku cli.raku) produces: +Usage: + cli.raku <name> +=end comment + +=begin comment +And since MAIN is a regular Raku sub, you can have multi-dispatch: +(using a `Bool` for the named argument so that we can do `--replace` +instead of `--replace=1`. The presence of `--replace` indicates truthness +while its absence falseness). For example: + + # convert to IO object to check the file exists + subset File of Str where *.IO.d; + + multi MAIN('add', $key, $value, Bool :$replace) { ... } + multi MAIN('remove', $key) { ... } + multi MAIN('import', File, Str :$as) { ... } # omitting parameter name + +Thus $ raku cli.raku produces: +Usage: + cli.raku [--replace] add <key> <value> + cli.raku remove <key> + cli.raku [--as=<Str>] import <File> + +As you can see, this is *very* powerful. It even went as far as to show inline +the constants (the type is only displayed if the argument is `$`/is named). +=end comment + +#################################################### +# 20. APPENDIX A: +#################################################### + +=begin comment +It's assumed by now you know the Raku basics. This section is just here to +list some common operations, but which are not in the "main part" of the +tutorial to avoid bloating it up. +=end comment + +# +# 20.1 Operators +# + +# Sort comparison - they return one value of the `Order` enum: `Less`, `Same` +# and `More` (which numerify to -1, 0 or +1 respectively). +say 1 <=> 4; # OUTPUT: «More», sort comparison for numerics +say 'a' leg 'b'; # OUTPUT: «Lessre», sort comparison for string +say 1 eqv 1; # OUTPUT: «Truere», sort comparison using eqv semantics +say 1 eqv 1.0; # OUTPUT: «False» + +# Generic ordering +say 3 before 4; # OUTPUT: «True» +say 'b' after 'a'; # OUTPUT: «True» + +# Short-circuit default operator - similar to `or` and `||`, but instead +# returns the first *defined* value: +say Any // Nil // 0 // 5; # OUTPUT: «0» + +# Short-circuit exclusive or (XOR) - returns `True` if one (and only one) of +# its arguments is true +say True ^^ False; # OUTPUT: «True» + +=begin comment +Flip flops. These operators (`ff` and `fff`, equivalent to P5's `..` +and `...`) are operators that take two predicates to test: They are `False` +until their left side returns `True`, then are `True` until their right +side returns `True`. Similar to ranges, you can exclude the iteration when +it become `True`/`False` by using `^` on either side. Let's start with an +example : +=end comment + +for <well met young hero we shall meet later> { + # by default, `ff`/`fff` smart-match (`~~`) against `$_`: + if 'met' ^ff 'meet' { # Won't enter the if for "met" + .say # (explained in details below). + } + + if rand == 0 ff rand == 1 { # compare variables other than `$_` + say "This ... probably will never run ..."; + } +} + +=begin comment +This will print "young hero we shall meet" (excluding "met"): the flip-flop +will start returning `True` when it first encounters "met" (but will still +return `False` for "met" itself, due to the leading `^` on `ff`), until it +sees "meet", which is when it'll start returning `False`. +=end comment + +=begin comment +The difference between `ff` (awk-style) and `fff` (sed-style) is that `ff` +will test its right side right when its left side changes to `True`, and can +get back to `False` right away (*except* it'll be `True` for the iteration +that matched) while `fff` will wait for the next iteration to try its right +side, once its left side changed: +=end comment + +# The output is due to the right-hand-side being tested directly (and returning +# `True`). "B"s are printed since it matched that time (it just went back to +# `False` right away). +.say if 'B' ff 'B' for <A B C B A>; # OUTPUT: «B B», + +# In this case the right-hand-side wasn't tested until `$_` became "C" +# (and thus did not match instantly). +.say if 'B' fff 'B' for <A B C B A>; #=> «B C B», + +# A flip-flop can change state as many times as needed: +for <test start print it stop not printing start print again stop not anymore> { + # exclude both "start" and "stop", + .say if $_ eq 'start' ^ff^ $_ eq 'stop'; # OUTPUT: «print it print again» +} + +# You might also use a Whatever Star, which is equivalent to `True` for the +# left side or `False` for the right, as shown in this example. +# NOTE: the parenthesis are superfluous here (sometimes called "superstitious +# parentheses"). Once the flip-flop reaches a number greater than 50, it'll +# never go back to `False`. +for (1, 3, 60, 3, 40, 60) { + .say if $_ > 50 ff *; # OUTPUT: «6034060» +} + +# You can also use this property to create an `if` that'll not go through the +# first time. In this case, the flip-flop is `True` and never goes back to +# `False`, but the `^` makes it *not run* on the first iteration +for <a b c> { .say if * ^ff *; } # OUTPUT: «bc» + +# The `===` operator, which uses `.WHICH` on the objects to be compared, is +# the value identity operator whereas the `=:=` operator, which uses `VAR()` on +# the objects to compare them, is the container identity operator. +``` + +If you want to go further and learn more about Raku, you can: + +- Read the [Raku Docs](https://docs.raku.org/). This is a great +resource on Raku. If you are looking for something, use the search bar. +This will give you a dropdown menu of all the pages referencing your search +term (Much better than using Google to find Raku documents!). + +- Read the [Raku Advent Calendar](http://perl6advent.wordpress.com/). This +is a great source of Raku snippets and explanations. If the docs don't +describe something well enough, you may find more detailed information here. +This information may be a bit older but there are many great examples and +explanations. Posts stopped at the end of 2015 when the language was declared +stable and Raku 6.c was released. + +- Come along on `#raku` at `irc.freenode.net`. The folks here are +always helpful. + +- Check the [source of Raku's functions and +classes](https://github.com/rakudo/rakudo/tree/nom/src/core). Rakudo is +mainly written in Raku (with a lot of NQP, "Not Quite Perl", a Raku subset +easier to implement and optimize). + +- Read [the language design documents](https://design.raku.org/). They explain +Raku from an implementor point-of-view, but it's still very interesting. + diff --git a/reason.html.markdown b/reason.html.markdown index 62d809cf..b8a2215d 100644 --- a/reason.html.markdown +++ b/reason.html.markdown @@ -162,7 +162,7 @@ let maxPassengers = firstTrip.capacity; /* If you define the record type in a different file, you have to reference the filename, if trainJourney was in a file called Trips.re */ -let secondTrip: Trips.firstTrip = { +let secondTrip: Trips.trainJourney = { destination: "Paris", capacity: 50, averageSpeed: 150.0, diff --git a/ru-ru/c++-ru.html.markdown b/ru-ru/c++-ru.html.markdown index 35994749..3acfafa3 100644 --- a/ru-ru/c++-ru.html.markdown +++ b/ru-ru/c++-ru.html.markdown @@ -43,11 +43,11 @@ int main(int argc, char** argv) // Аргументы командной строки, переданные в программу, хранятся в переменных // argc и argv, так же, как и в C. // argc указывает на количество аргументов, - // а argv является массивом C-подобных строк (char*), который непосредсвенно + // а argv является массивом C-подобных строк (char*), который непосредственно // содержит аргументы. // Первым аргументом всегда передается имя программы. - // argc и argv могут быть опущены, если вы не планируете работать с аругментами - // коммандной строки. + // argc и argv могут быть опущены, если вы не планируете работать с аргументами + // командной строки. // Тогда сигнатура функции будет иметь следующий вид: int main() // Возвращаемое значение 0 указывает на успешное завершение программы. @@ -162,7 +162,7 @@ void foo() int main() { - // Включает все функци из пространства имен Second в текущую область видимости. + // Включает все функции из пространства имен Second в текущую область видимости. // Обратите внимание, что простой вызов foo() больше не работает, // так как теперь не ясно, вызываем ли мы foo из пространства имен Second, или // из глобальной области видимости. @@ -471,6 +471,7 @@ int main() { // членам\методам без открытых или защищенных методов для этого. class OwnedDog : public Dog { +public: void setOwner(const std::string& dogsOwner); // Переопределяем поведение функции печати для всех OwnedDog. Смотрите @@ -582,10 +583,10 @@ public: // Во время компиляции компилятор фактически генерирует копии каждого шаблона // с замещенными параметрами, поэтому полное определение класса должно присутствовать -// при каждом вызове. Именно поэтому классы шаблонов полностью определены в +// при каждом вызове. Именно поэтому шаблоны классов полностью определены в // заголовочных файлах. -// Чтобы создать экземпляр класса шаблона на стеке: +// Чтобы создать экземпляр шаблона класса на стеке: Box<int> intBox; // и вы можете использовать его, как и ожидалось: @@ -605,7 +606,7 @@ boxOfBox.insert(intBox); // http://en.wikipedia.org/wiki/Typename // (да-да, это ключевое слово имеет собственную страничку на вики). -// Аналогичным образом, шаблонная функция: +// Аналогичным образом, шаблон функции: template<class T> void barkThreeTimes(const T& input) { @@ -622,7 +623,7 @@ Dog fluffy; fluffy.setName("Fluffy"); barkThreeTimes(fluffy); // Печатает "Fluffy barks" три раза. -//Параметры шаблона не должны быть классами: +// Параметры шаблона не должны быть классами: template<int Y> void printMessage() { cout << "Learn C++ in " << Y << " minutes!" << endl; @@ -680,7 +681,7 @@ catch (...) // некоторого ресурса неразрывно совмещается с инициализацией, а освобождение - // с уничтожением объекта. -// Чтобы понять, на сколько это полезно, +// Чтобы понять, насколько это полезно, // рассмотрим функцию, которая использует обработчик файлов в С: void doSomethingWithAFile(const char* filename) { @@ -796,7 +797,7 @@ void doSomethingWithAFile(const std::string& filename) // - Контейнеры - стандартная библиотека связанных списков, векторы // (т.е. самоизменяемые массивы), хэш-таблицы и все остальное автоматически // уничтожается сразу же, когда выходит за пределы области видимости. -// - Ипользование мьютексов lock_guard и unique_lock +// - Использование мьютексов lock_guard и unique_lock // Контейнеры с пользовательскими классами в качестве ключей требуют // сравнивающих функций в самом объекте или как указатель на функцию. Примитивы diff --git a/ru-ru/c-ru.html.markdown b/ru-ru/c-ru.html.markdown index 44e7ad3b..389c8bc9 100644 --- a/ru-ru/c-ru.html.markdown +++ b/ru-ru/c-ru.html.markdown @@ -77,7 +77,7 @@ int main() { // sizeof(obj) возвращает размер объекта obj в байтах. printf("%zu\n", sizeof(int)); // => 4 (на большинстве машин int занимает 4 байта) - // Если аргуметом sizeof будет выражение, то этот аргумент вычисляется + // Если аргументом sizeof будет выражение, то этот аргумент вычисляется // ещё во время компиляции кода (кроме динамических массивов). int a = 1; // size_t это беззнаковый целый тип который использует как минимум 2 байта @@ -308,7 +308,7 @@ int main() { // Это работает, потому что при обращении к имени массива возвращается // указатель на первый элемент. // Например, когда массив передаётся в функцию или присваивается указателю, он - // неяввно преобразуется в указатель. + // неявно преобразуется в указатель. // Исключения: когда массив является аргументом для оператор '&': int arr[10]; int (*ptr_to_arr)[10] = &arr; // &arr не является 'int *'! @@ -335,7 +335,7 @@ int main() { // Работа с памятью с помощью указателей может давать неожиданные и // непредсказуемые результаты. - printf("%d\n", *(my_ptr + 21)); // => Напечатает кто-нибудь-знает-что? + printf("%d\n", *(my_ptr + 21)); // => Напечатает кто-нибудь знает, что? // Скорей всего программа вылетит. // Когда вы закончили работать с памятью, которую ранее выделили, вам необходимо @@ -426,7 +426,7 @@ void function_1() { // Можно получить доступ к структуре и через указатель (*my_rec_ptr).width = 30; - // ... или ещё лучше: используйте оператор -> для лучшей читабельночти + // ... или ещё лучше: используйте оператор -> для лучшей читабельности my_rec_ptr->height = 10; // то же что и "(*my_rec_ptr).height = 10;" } diff --git a/ru-ru/go-ru.html.markdown b/ru-ru/go-ru.html.markdown index 6c8622cc..37592258 100644 --- a/ru-ru/go-ru.html.markdown +++ b/ru-ru/go-ru.html.markdown @@ -35,7 +35,7 @@ package main // Import предназначен для указания зависимостей этого файла. import ( "fmt" // Пакет в стандартной библиотеке Go - "io/ioutil" // Реализация функций ввод/ввывода. + "io/ioutil" // Реализация функций ввод/вывода. "net/http" // Да, это веб-сервер! "strconv" // Конвертирование типов в строки и обратно m "math" // Импортировать math под локальным именем m. @@ -270,7 +270,7 @@ func learnErrorHandling() { // c – это тип данных channel (канал), объект для конкурентного взаимодействия. func inc(i int, c chan int) { - c <- i + 1 // когда channel слева, <- являтся оператором "отправки". + c <- i + 1 // когда channel слева, <- является оператором "отправки". } // Будем использовать функцию inc для конкурентной инкрементации чисел. diff --git a/ru-ru/rust-ru.html.markdown b/ru-ru/rust-ru.html.markdown index 16b635f0..9293a40e 100644 --- a/ru-ru/rust-ru.html.markdown +++ b/ru-ru/rust-ru.html.markdown @@ -6,36 +6,33 @@ contributors: - ["P1start", "http://p1start.github.io/"] translators: - ["Anatolii Kosorukov", "https://github.com/java1cprog"] + - ["Vasily Starostin", "https://github.com/Basil22"] lang: ru-ru --- -Rust сочетает в себе низкоуровневый контроль над производительностью с удобством высокого уровня и предоставляет гарантии -безопасности. -Он достигает этих целей, не требуя сборщика мусора или времени выполнения, что позволяет использовать библиотеки Rust как замену -для C-библиотек. +Язык Rust разработан в Mozilla Research. Он сочетает низкоуровневую производительность с удобством языка высокого уровня и одновременно гарантирует безопасность памяти. -Первый выпуск Rust, 0.1, произошел в январе 2012 года, и в течение 3 лет развитие продвигалось настолько быстро, что до -недавнего времени использование стабильных выпусков было затруднено, и вместо этого общий совет заключался в том, чтобы -использовать последние сборки. +Он достигает этих целей без сборщика мусора или сложной среды выполнения, что позволяет использовать библиотеки Rust как прямую замену +C-библиотек. И наоборот, Rust умеет использовать готовые С-библиотеки как есть, без накладных расходов. -15 мая 2015 года был выпущен Rust 1.0 с полной гарантией обратной совместимости. Усовершенствования времени компиляции и -других аспектов компилятора в настоящее время доступны в ночных сборках. Rust приняла модель выпуска на поезде с регулярными выпусками каждые шесть недель. Rust 1.1 beta был доступен одновременно с выпуском Rust 1.0. +Первый выпуск Rust, 0.1, произошел в январе 2012 года. В течение 3 лет развитие продвигалось настолько быстро, что язык серьезно менялся без сохранения совместимости. Это дало возможность обкатать и отполировать синтаксис и возможности языка. -Хотя Rust является языком относительно низкого уровня, Rust имеет некоторые функциональные концепции, которые обычно -встречаются на языках более высокого уровня. Это делает Rust не только быстрым, но и простым и эффективным для ввода кода. +15 мая 2015 года был выпущен Rust 1.0 с полной гарантией обратной совместимости. Сборка поставляется в трех вариантах: стабильная версия, бета-версия, ночная версия. Все нововведения языка сперва обкатываются на ночной и бета-версиях, и только потом попадают в стабильную. Выход очередной версии происходит раз в 6 недель. В 2018 году вышло второе большое обновление языка, добавившее ему новых возможностей. + +Хотя Rust является языком относительно низкого уровня, он имеет все возможности высокоуровневых языков: процедурное, объектное, функциональное, шаблонное и другие виды программирования. На данный момент Rust является одним из самых мощных (а может быть и самым) по возможностям среди статически типизированных языков. Это делает Rust не только быстрым, но и простым и эффективным для разработки сложного кода. ```rust -// Это однострочный комментарии +// Это однострочный комментарий // /// Так выглядит комментарий для документации /// # Examples /// -/// +/// ``` /// let seven = 7 -/// +/// ``` /////////////// // 1. Основы // @@ -63,10 +60,9 @@ fn main() { let y: i32 = 13i32; let f: f64 = 1.3f64; - // Автоматическое выявление типа данных + // Автоматическое выведение типа данных // В большинстве случаев компилятор Rust может вычислить - // тип переменной, поэтому - // вам не нужно писать явные аннотации типа. + // тип переменной, поэтому вам не нужно явно указывать тип. let implicit_x = 1; let implicit_f = 1.3; @@ -87,12 +83,11 @@ fn main() { // Печать на консоль println!("{} {}", f, x); // 1.3 hello world - // `String` – изменяемя строка + // `String` – изменяемая строка let s: String = "hello world".to_string(); - // Строковый срез - неизменяемый вид в строки - // Это в основном неизменяемая пара указателей на строку - - // Это указатель на начало и конец строкового буфера + // Строковый срез - неизменяемое представление части строки + // Представляет собой пару из указателя на начало фрагмента и его длины let s_slice: &str = &s; @@ -154,6 +149,8 @@ fn main() { let up = Direction::Up; // Перечисление с полями + // В отличие от C и C++ компилятор автоматически следит за тем, + // какой именно тип хранится в перечислении. enum OptionalI32 { AnI32(i32), Nothing, @@ -198,9 +195,9 @@ fn main() { let another_foo = Foo { bar: 1 }; println!("{:?}", another_foo.frobnicate()); // Some(1) - ///////////////////////// - // 3. Поиск по шаблону // - ///////////////////////// + ///////////////////////////////// + // 3. Сопоставление по шаблону // + ///////////////////////////////// let foo = OptionalI32::AnI32(1); match foo { @@ -223,9 +220,9 @@ fn main() { println!("The second number is Nothing!"), } - ///////////////////// + ////////////////////////////////////////////// // 4. Управление ходом выполнения программы // - ///////////////////// + ////////////////////////////////////////////// // `for` loops/iteration let array = [1, 2, 3]; @@ -266,12 +263,12 @@ fn main() { break; } - ///////////////////////////////// + ////////////////////////////////// // 5. Защита памяти и указатели // - ///////////////////////////////// + ////////////////////////////////// // Владеющий указатель – такой указатель может быть только один - // Это значит, что при вызоде из блока переменная автоматически становится недействительной. + // Это значит, что при выходе из блока переменная автоматически становится недействительной. let mut mine: Box<i32> = Box::new(3); *mine = 5; // dereference // Здесь, `now_its_mine` получает во владение `mine`. Т.е. `mine` была перемещена. diff --git a/ru-ru/yaml-ru.html.markdown b/ru-ru/yaml-ru.html.markdown index 6eb580d9..0f805681 100644 --- a/ru-ru/yaml-ru.html.markdown +++ b/ru-ru/yaml-ru.html.markdown @@ -24,7 +24,7 @@ YAML как язык сериализации данных предназнач # Скалярные величины # ###################### -# Наш корневой объект (который продолжается для всего документа) будет соответствовать +# Наш корневой объект (который продолжается до конца документа) будет соответствовать # типу map, который в свою очередь соответствует словарю, хешу или объекту в других языках. key: value another_key: Другое значение ключа. diff --git a/ruby.html.markdown b/ruby.html.markdown index d77672ab..f437adcf 100644 --- a/ruby.html.markdown +++ b/ruby.html.markdown @@ -410,7 +410,7 @@ def guests(&block) end # The 'call' method on the Proc is similar to calling 'yield' when a block is -# present. The arguments passed to 'call' will be forwarded to the block as arugments. +# present. The arguments passed to 'call' will be forwarded to the block as arguments. guests { |n| "You have #{n} guests." } # => "You have 4 guests." diff --git a/zh-cn/yaml-cn.html.markdown b/zh-cn/yaml-cn.html.markdown index de933d12..3ba2afd8 100644 --- a/zh-cn/yaml-cn.html.markdown +++ b/zh-cn/yaml-cn.html.markdown @@ -33,8 +33,13 @@ scientific_notation: 1e+12 boolean: true null_value: null key with spaces: value -# 注意到字符串不需要被括在引号中。但是，它们可以被括起来。 -"Keys can be quoted too.": "Useful if you want to put a ':' in your key." +# 注意，字符串不必被括在引号中，但也可以被括起来。 +however: 'A string, enclosed in quotes.' +'Keys can be quoted too.': "Useful if you want to put a ':' in your key." +single quotes: 'have ''one'' escape pattern' +double quotes: "have many: \", \0, \t, \u263A, \x0d\x0a == \r\n, and more." +# UTF-8/16/32 字符需要被转义(encoded) +Superscript two: \u00B2 # 多行字符串既可以写成像一个'文字块'(使用 |)， # 或像一个'折叠块'(使用 '>')。 @@ -73,8 +78,8 @@ a_nested_map: # 键也可以是复合型的，比如多行对象 # 我们用 ? 后跟一个空格来表示一个复合键的开始。 ? | - This is a key - that has multiple lines + This is a key + that has multiple lines : and this is its value # YAML 也允许使用复杂键语法表示序列间的映射关系。 @@ -85,6 +90,7 @@ a_nested_map: : [ 2001-01-01, 2002-02-02 ] # 序列 (等价于列表或数组) 看起来像这样： +# 注意 '-' 算作缩进 a_sequence: - Item 1 - Item 2 @@ -95,6 +101,8 @@ a_sequence: - - This is a sequence - inside another sequence + - - - Nested sequence indicators + - can be collapsed # 因为 YAML 是 JSON 的超集，你也可以写 JSON 风格的映射和序列： json_map: {"key": "value"} @@ -157,15 +165,18 @@ gif_file: !!binary | # YAML 还有一个集合类型，它看起来像这样： set: - ? item1 - ? item2 - ? item3 + ? item1 + ? item2 + ? item3 +or: {item1, item2, item3} # 集合只是值为 null 的映射；上面的集合等价于： set2: - item1: null - item2: null - item3: null + item1: null + item2: null + item3: null + +... # document end ``` ### 更多资源 |