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| -rw-r--r-- | perl6.html.markdown | 173 |
1 files changed, 131 insertions, 42 deletions
diff --git a/perl6.html.markdown b/perl6.html.markdown index e813978a..7485ed57 100644 --- a/perl6.html.markdown +++ b/perl6.html.markdown @@ -25,14 +25,20 @@ double paragraphs, and single notes. Multiline comments use #` and a quoting construct. (), [], {}, 「」, etc, will work. ) +``` -### Variables +## Variables +```perl6 # In Perl 6, you declare a lexical variable using `my` my $variable; # Perl 6 has 4 kinds of variables: +``` -## * Scalars. They represent a single value. They start with a `$` +### Scalars + +```perl6 +# Scalars represent a single value. They start with a `$` my $str = 'String'; # double quotes allow for interpolation (which we'll see later): @@ -46,8 +52,12 @@ my $bool = True; # `True` and `False` are Perl 6's boolean values. my $inverse = !$bool; # You can invert a bool with the prefix `!` operator my $forced-bool = so $str; # And you can use the prefix `so` operator # which turns its operand into a Bool +``` -## * Lists. They represent multiple values. Their name start with `@`. +### Lists + +```perl6 +# Lists represent multiple values. Their name start with `@`. my @array = 'a', 'b', 'c'; # equivalent to : @@ -66,8 +76,11 @@ say "Interpolate all elements of an array using [] : @array[]"; my @keys = 0, 2; @array[@keys] = @letters; # Assignment using an array containing index values say @array; #=> a 6 b +``` -## * Hashes, or key-value Pairs. +### 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. @@ -96,9 +109,13 @@ my %hash = :w(1), # equivalent to `w => 1` say %hash{'key1'}; # You can use {} to get the value from a key say %hash<key2>; # If it's a string, you can actually use <> # (`{key1}` doesn't work, as Perl6 doesn't have barewords) +``` -## * Subs: subroutines or functions as most other languages call them are -# created with the `sub` keyword. +## Subs + +```perl6 +# subroutines or functions as most other languages call them are +# created with the `sub` keyword. sub say-hello { say "Hello, world" } sub say-hello-to(Str $name) { # You can provide the type of an argument @@ -186,8 +203,11 @@ sub concat3($a, $b, $c) { } concat3(|@array); #=> a, b, c # `@array` got "flattened" as a part of the argument list +``` -### Containers +## 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. @@ -216,11 +236,12 @@ 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 -### Control Flow Structures -## Conditionals - +```perl6 # - `if` # Before talking about `if`, we need to know which values are "Truthy" # (represent True), and which are "Falsey" (or "Falsy") -- represent False. @@ -249,7 +270,11 @@ say "Quite truthy" if True; my $age = 30; say $age > 18 ?? "You are an adult" !! "You are under 18"; +``` +### given/when, or switch + +```perl6 # - `given`-`when` looks like other languages' `switch`, but is much more # powerful thanks to smart matching and Perl 6's "topic variable", $_. # @@ -282,9 +307,11 @@ given "foo bar" { say "Something else" } } +``` -## Looping constructs +### 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 { @@ -327,9 +354,11 @@ for @array { if long-computation() -> $result { say "The result is $result"; } +``` -### Operators +## 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). @@ -448,12 +477,18 @@ $b || $a; # 1 $a *= 2; # multiply and assignment. Equivalent to $a = $a * 2; $b %%= 5; # divisible by and assignment @array .= sort; # calls the `sort` method and assigns the result back +``` + +## More on subs ! -### More on subs ! +```perl6 # As we said before, Perl 6 has *really* powerful subs. We're going to see # a few more key concepts that make them better than in any other language :-). +``` + +### Unpacking ! -## Unpacking ! +```perl6 # It's the ability to "extract" arrays and keys (AKA "destructuring"). # It'll work in `my`s and in parameter lists. my ($f, $g) = 1, 2; @@ -521,7 +556,11 @@ sub list-of($n) { } } my @list3 = list-of(3); #=> (0, 1, 2) +``` + +### lambdas +```perl6 ## You can create a lambda with `-> {}` ("pointy block") or `{}` ("block") my &lambda = -> $argument { "The argument passed to this lambda is $argument" } # `-> {}` and `{}` are pretty much the same thing, except that the former can @@ -564,8 +603,11 @@ map(sub ($a, $b) { $a + $b + 3 }, @array); # (here with `sub`) # Note : those are sorted lexicographically. # `{ $^b / $^a }` is like `-> $a, $b { $b / $a }` +``` + +### About types... -## About types... +```perl6 # Perl6 is gradually typed. This means you can specify the type # of your variables/arguments/return types, or you can omit them # and they'll default to "Any". @@ -579,8 +621,11 @@ map(sub ($a, $b) { $a + $b + 3 }, @array); # (here with `sub`) # You can specify the type you're subtyping (by default, Any), # and add additional checks with the "where" keyword: subset VeryBigInteger of Int where * > 500; +``` + +### Multiple Dispatch -## 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 a `where`: @@ -624,9 +669,11 @@ multi with-or-without-you { # sub trait_mod:<is>(Routine $r, :$rw!) {} # # (commented because running this would be a terrible idea !) +``` +## Scoping -### 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, @@ -646,9 +693,11 @@ outer()(); #=> 'Foo Bar' # As you can see, `$file_scoped` and `$outer_scoped` were captured. # But if we were to try and use `$bar` outside of `foo`, # the variable would be undefined (and you'd get a compile time error). +``` -### Twigils +## Twigils +```perl6 # There are many special `twigils` (composed sigil's) in Perl 6. # Twigils define the variables' scope. # The * and ? twigils work on standard variables: @@ -683,9 +732,11 @@ call_say_dyn(); #=> 25 100 # 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 +## 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 @@ -730,8 +781,11 @@ say $class-obj.get-value; #=> 15 #$class-obj.attrib = 5; # This fails, because the `has $.attrib` is immutable $class-obj.other-attrib = 10; # This, however, works, because the public # attribute is mutable (`rw`). +``` + +### Object Inheritance -## Object Inheritance +```perl6 # Perl 6 also has inheritance (along with multiple inheritance) # While `method`'s are inherited, `submethod`'s are not. # Submethods are useful for object construction and destruction tasks, @@ -768,9 +822,12 @@ $Madison.talk; # prints "Goo goo ga ga" due to the overrided method. # `$a .= b` is the same as `$a = $a.b`) # Also note that `BUILD` (the method called inside `new`) # will set parent properties too, so you can pass `val => 5`. +``` +### Roles, or Mixins -## Roles are supported too (also called Mixins in other languages) +```perl6 +# Roles are supported too (also called Mixins in other languages) role PrintableVal { has $!counter = 0; method print { @@ -798,8 +855,11 @@ class Item does PrintableVal { # 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 -### 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 @@ -828,8 +888,11 @@ open 'foo' orelse say "Something happened $_"; #> Something happened # Both of those above work but in case we get an object from the left side that # is not a failure we will probably get a warning. We see below how we can use # `try` and `CATCH` to be more specific with the exceptions we catch. +``` + +### Using `try` and `CATCH` -## Using `try` and `CATCH` +```perl6 # By using `try` and `CATCH` you can contain and handle exceptions without # disrupting the rest of the program. `try` will set the last exception to # the special variable `$!` Note: This has no relation to $!variables. @@ -883,8 +946,11 @@ try { # 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 -### 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) @@ -915,8 +981,11 @@ grammar Parse::Text::Grammar { # A grammar is a package, which you could `use` my $actions = JSON::Tiny::Actions.new; # We'll see how to export variables and subs in the next part: +``` + +## Declarators -### 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. @@ -978,10 +1047,11 @@ for ^5 -> $a { # Next iteration will re-run `rand`. } } +``` +## Phasers - -### 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, @@ -1041,8 +1111,11 @@ sub do-db-stuff { KEEP $db.commit; # commit the transaction if all went well UNDO $db.rollback; # or rollback if all hell broke loose } +``` + +## Statement prefixes -### 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 somewhere else) @@ -1085,8 +1158,11 @@ say join ',', gather if False { constant thrice = gather for ^3 { say take $_ }; # Doesn't print anything # versus: constant thrice = eager gather for ^3 { say take $_ }; #=> 0 1 2 +``` + +## Iterables -### Iterables +```perl6 # Iterables are objects that can be iterated similar to the `for` construct # `flat`, flattens iterables: say (1, 10, (20, 10) ); #> (1 10 (20 10)) Notice how grouping is maintained @@ -1108,9 +1184,11 @@ quietly { warn 'This is a warning!' }; #=> No output # - `contend` - Attempts side effects under STM # Not yet implemented ! +``` -### More operators thingies ! +## More operators thingies ! +```perl6 ## Everybody loves operators ! Let's get more of them # The precedence list can be found here: @@ -1128,8 +1206,11 @@ $a ! $b ! $c; # with a list-associative `!`, this is `infix:<>` !$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 ! +### Create your own operators ! + +```perl6 # Okay, you've been reading all of that, so I guess I should try # to show you something exciting. # I'll tell you a little secret (or not-so-secret): @@ -1193,8 +1274,11 @@ postcircumfix:<{ }>(%h, $key, :delete); # (you can call operators like that) # (you are, obviously, recommended against making an operator out of # *everything* -- with great power comes great responsibility) +``` -## Meta operators ! +### 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 that. @@ -1281,8 +1365,11 @@ say @fib[^10]; #=> 1 1 2 3 5 8 13 21 34 55 # 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 be instant. +``` -### Regular Expressions +## 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). @@ -1402,8 +1489,11 @@ so 'foo' ~~ / <-[ f o ]> + /; # False 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 +### Grouping and capturing + +```perl6 # Group: you can group parts of your regexp with `[]`. # These groups are *not* captured (like PCRE's `(?:)`). so 'abc' ~~ / a [ b ] c /; # `True`. The grouping does pretty much nothing @@ -1478,7 +1568,7 @@ so 'ayc' ~~ / a [ b | y ] c /; # `True`. Obviously enough ... # and other things that can't traditionnaly be represented by normal regexps. # # Then, all the alternatives are tried at once, and the longest wins. -# Exemples: +# Examples: # DECLARATIVE | PROCEDURAL / 'foo' \d+ [ <subrule1> || <subrule2> ] /; # DECLARATIVE (nested groups are not a problem) @@ -1489,11 +1579,11 @@ so 'ayc' ~~ / a [ b | y ] c /; # `True`. Obviously enough ... # Note: the first-matching `or` still exists, but is now spelled `||` 'foo' ~~ / fo || foo /; # `fo` now. +``` +## Extra: the MAIN subroutine - - -### 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`) @@ -1521,13 +1611,12 @@ multi MAIN('import', File, Str :$as) { ... } # omitting parameter name # 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: -### +## APPENDIX A: ### List of things -### +```perl6 # It's considered 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 bloat it up |