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diff --git a/nim.html.markdown b/nim.html.markdown new file mode 100644 index 00000000..c9548a1c --- /dev/null +++ b/nim.html.markdown @@ -0,0 +1,273 @@ +--- +language: Nim +filename: learnNim.nim +contributors: + - ["Jason J. Ayala P.", "http://JasonAyala.com"] + - ["Dennis Felsing", "http://felsin9.de/nnis/"] +--- + +Nim (formerly Nimrod) is a statically typed, imperative programming language +that gives the programmer power without compromises on runtime efficiency. + +Nim is efficient, expressive, and elegant. + +```nimrod +var # Declare (and assign) variables, + letter: char = 'n' # with or without type annotations + lang = "N" & "im" + nLength : int = len(lang) + boat: float + truth: bool = false + +let # Use let to declare and bind variables *once*. + legs = 400 # legs is immutable. + arms = 2_000 # _ are ignored and are useful for long numbers. + aboutPi = 3.15 + +const # Constants are computed at compile time. This provides + debug = true # performance and is useful in compile time expressions. + compileBadCode = false + +when compileBadCode: # `when` is a compile time `if` + legs = legs + 1 # This error will never be compiled. + const input = readline(stdin) # Const values must be known at compile time. + +discard 1 > 2 # Note: The compiler will complain if the result of an expression + # is unused. `discard` bypasses this. + +discard """ +This can work as a multiline comment. +Or for unparsable, broken code +""" + +# +# Data Structures +# + +# Tuples + +var + child: tuple[name: string, age: int] # Tuples have *both* field names + today: tuple[sun: string, temp: float] # *and* order. + +child = (name: "Rudiger", age: 2) # Assign all at once with literal () +today.sun = "Overcast" # or individual fields. +today.temp = 70.1 + +# Sequences + +var + drinks: seq[string] + +drinks = @["Water", "Juice", "Chocolate"] # @[V1,..,Vn] is the sequence literal + +drinks.add("Milk") + +if "Milk" in drinks: + echo "We have Milk and ", drinks.len - 1, " other drinks" + +let myDrink = drinks[2] + +# +# Defining Types +# + +# Defining your own types puts the compiler to work for you. It's what makes +# static typing powerful and useful. + +type + Name = string # A type alias gives you a new type that is interchangable + Age = int # with the old type but is more descriptive. + Person = tuple[name: Name, age: Age] # Define data structures too. + AnotherSyntax = tuple + fieldOne: string + secondField: int + +var + john: Person = (name: "John B.", age: 17) + newage: int = 18 # It would be better to use Age than int + +john.age = newage # But still works because int and Age are synonyms + +type + Cash = distinct int # `distinct` makes a new type incompatible with its + Desc = distinct string # base type. + +var + money: Cash = 100.Cash # `.Cash` converts the int to our type + description: Desc = "Interesting".Desc + +when compileBadCode: + john.age = money # Error! age is of type int and money is Cash + john.name = description # Compiler says: "No way!" + +# +# More Types and Data Structures +# + +# Enumerations allow a type to have one of a limited number of values + +type + Color = enum cRed, cBlue, cGreen + Direction = enum # Alternative formating + dNorth + dWest + dEast + dSouth +var + orient = dNorth # `orient` is of type Direction, with the value `dNorth` + pixel = cGreen # `pixel` is of type Color, with the value `cGreen` + +discard dNorth > dEast # Enums are usually an "ordinal" type + +# Subranges specify a limited valid range + +type + DieFaces = range[1..20] # Only an int from 1 to 20 is a valid value +var + my_roll: DieFaces = 13 + +when compileBadCode: + my_roll = 23 # Error! + +# Arrays + +type + RollCounter = array[DieFaces, int] # Array's are fixed length and + DirNames = array[Direction, string] # indexed by any ordinal type. + Truths = array[42..44, bool] +var + counter: RollCounter + directions: DirNames + possible: Truths + +possible = [false, false, false] # Literal arrays are created with [V1,..,Vn] +possible[42] = true + +directions[dNorth] = "Ahh. The Great White North!" +directions[dWest] = "No, don't go there." + +my_roll = 13 +counter[my_roll] += 1 +counter[my_roll] += 1 + +var anotherArray = ["Default index", "starts at", "0"] + +# More data structures are available, including tables, sets, lists, queues, +# and crit bit trees. +# http://nim-lang.org/docs/lib.html#collections-and-algorithms + +# +# IO and Control Flow +# + +# `case`, `readLine()` + +echo "Read any good books lately?" +case readLine(stdin) +of "no", "No": + echo "Go to your local library." +of "yes", "Yes": + echo "Carry on, then." +else: + echo "That's great; I assume." + +# `while`, `if`, `continue`, `break` + +import strutils as str # http://nim-lang.org/docs/strutils.html +echo "I'm thinking of a number between 41 and 43. Guess which!" +let number: int = 42 +var + raw_guess: string + guess: int +while guess != number: + raw_guess = readLine(stdin) + if raw_guess == "": continue # Skip this iteration + guess = str.parseInt(raw_guess) + if guess == 1001: + echo("AAAAAAGGG!") + break + elif guess > number: + echo("Nope. Too high.") + elif guess < number: + echo(guess, " is too low") + else: + echo("Yeeeeeehaw!") + +# +# Iteration +# + +for i, elem in ["Yes", "No", "Maybe so"]: # Or just `for elem in` + echo(elem, " is at index: ", i) + +for k, v in items(@[(person: "You", power: 100), (person: "Me", power: 9000)]): + echo v + +let myString = """ +an <example> +`string` to +play with +""" # Multiline raw string + +for line in splitLines(myString): + echo(line) + +for i, c in myString: # Index and letter. Or `for j in` for just letter + if i mod 2 == 0: continue # Compact `if` form + elif c == 'X': break + else: echo(c) + +# +# Procedures +# + +type Answer = enum aYes, aNo + +proc ask(question: string): Answer = + echo(question, " (y/n)") + while true: + case readLine(stdin) + of "y", "Y", "yes", "Yes": + return Answer.aYes # Enums can be qualified + of "n", "N", "no", "No": + return Answer.aNo + else: echo("Please be clear: yes or no") + +proc addSugar(amount: int = 2) = # Default amount is 2, returns nothing + assert(amount > 0 or amount < 9000, "Crazy Sugar") + for a in 1..amount: + echo(a, " sugar...") + +case ask("Would you like sugar in your tea?") +of aYes: + addSugar(3) +of aNo: + echo "Oh do take a little!" + addSugar() +# No need for an `else` here. Only `yes` and `no` are possible. + +# +# FFI +# + +# Because Nim compiles to C, FFI is easy: + +proc strcmp(a, b: cstring): cint {.importc: "strcmp", nodecl.} + +let cmp = strcmp("C?", "Easy!") +``` + +Additionally, Nim separates itself from its peers with metaprogramming, +performance, and compile-time features. + +## Further Reading + +* [Home Page](http://nim-lang.org) +* [Download](http://nim-lang.org/download.html) +* [Community](http://nim-lang.org/community.html) +* [FAQ](http://nim-lang.org/question.html) +* [Documentation](http://nim-lang.org/documentation.html) +* [Manual](http://nim-lang.org/docs/manual.html) +* [Standard Library](http://nim-lang.org/docs/lib.html) +* [Rosetta Code](http://rosettacode.org/wiki/Category:Nim) |