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260 lines
6.2 KiB
Markdown
260 lines
6.2 KiB
Markdown
---
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language: nim
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filename: learnNim.c
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contributors:
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- ["Jason J. Ayala P.", "http://JasonAyala.com"]
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---
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Nim is a statically typed, imperative programming language that tries to give
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the programmer ultimate power without compromises on runtime efficiency. This
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means it focuses on compile-time mechanisms in all their various forms.
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Nim is efficient, expressive, and elegant.
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```nimrod
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var x: int # Declare a variable and its type
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x = 1 # Assign it a value
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var z = "Yep" # Declare and assign, with or without type annotations
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var # Several, with or without type annotations
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letter: char = 'n' # One byte character
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name = "Nimrod" # string
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truth: bool = false # Common boolean operators: `and` `not` `or`
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seconds: int = 42
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thoughts = """
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A great programming language
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that everyone can enjoy!
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""" # Multiline raw strings
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boat: float
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let # Use let to declare and bind an variable *once*.
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legs = 400 # legs is immutable.
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arms = 2_000 # _ are ignored and are useful for long numbers.
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const # Constants are computed at compile time. This provides
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debug = true # performance and is useful in compile time expressions.
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aboutPi = 3.15
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compileBadCode = false
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when compileBadCode: # `when` is a compile time `if`
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legs = legs + 1 # This error will never be compiled.
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const input = readline(stdin) # const values must be known at compile time.
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discard 1 > 2 # The compiler will complain if the result of an expression
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# is unused. `discard` bypasses this.
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discard """
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This can work as a
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multiline comment
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"""
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#
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# Common Operations on Basic Types
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#
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var nim = "Nimrod is a progamming language"
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name = nim[0..5]
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# TODO More common operations?
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#
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# Data Structures
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#
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# Tuples
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var
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child: tuple[name: string, age: int] # Tuples have *both* field names
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today: tuple[sun: string, temp: float] # *and* order.
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child = (name: "Rudiger", age: 2) # Assign all at once with literal ()
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today.sun = "Overcast" # or individual fields.
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today.temp = 70.1
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# Sequences
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var
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drinks: seq[string]
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drinks = @["Water", "Juice", "Chocolate"] # @[V1,..,Vn] is the sequence literal
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#
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# Defining Your Own Types
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#
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# Defining your own types puts the compiler to work for you. It's what makes
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# static typing powerful and useful.
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type
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Name = string # A type alias gives you a new type that is interchangable
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Age = int # with the old type but is more descriptive.
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Person = tuple[name: Name, age: Age] # Define data structures too.
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var
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john: Person = ("John B.", 17)
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newage: int = 18 # It would be better to use Age than int
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john.age = newage # But still works because int and Age are synonyms
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type
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Cash = distinct int # `distinct` makes a new type incompatible with it's
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Desc = distinct string # base type.
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var
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money: Cash = 100.Cash # `.Cash` converts the int to our type
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desc: Desc = "Interesting".Desc
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when compileBadCode:
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john.age = money # Error! age is of type int and money is Cash
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john.name = desc # Compiler says: "No way!"
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#
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# More Types and Data Structures
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#
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# Enumerations allow a type to be one of a limited number of values
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type
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Directions = enum north, west, east, south
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Colors = enum red, blue, green
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var
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orient = north # `orient` is of type Directions, with the value `north`
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pixel = green # `pixel` is of type Colors, with the value `green`
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discard north > east # Enums are usually an "ordinal" type
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# Subranges specify a limited valid range
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type
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DieFaces = range[1..20] # Only an int from 1 to 20 is a valid value
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var
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my_roll: DieFaces = 13
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when compileBadCode:
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my_roll = 23 # Error!
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# Arrays
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type
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RollCounter = array[DieFaces, int] # Array's are fixed length and
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DirNames = array[Directions, string] # indexed by any ordinal type.
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Truths = array[42..44, bool]
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var
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rollCounter: RollCounter
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directions: DirNames
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truths: Truths
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truths = [false, false, false] # Literal arrays are created with [V1,..,Vn]
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truths[42] = true
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directions[north] = "Ahh. The Great White North!"
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directions[west] = "No, don't go there."
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my_roll = 13
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rollCounter[my_roll] += 1
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rollCounter[my_roll] += 1
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var anotherArray = ["Default index", "starts at", "0"]
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# TODO common operations
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#
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# IO and Control Flow
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#
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# `case`, `readLine()`
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echo "Read any good books lately?"
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case readLine(stdin)
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of "no", "No":
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echo "Go to your local library."
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of "yes", "Yes":
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echo "Carry on, then."
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else:
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echo "That's great; I assume."
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# `while`, `if`, `continue`, `break`
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import strutils as str
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echo "I'm thinking of a number between 41 and 43. Guess which!"
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var
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answer: int = 42
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raw_guess: string
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guess: int
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while guess != answer:
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raw_guess = readLine(stdin)
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if raw_guess == "":
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continue # `continue` restarts loop/block
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guess = str.parseInt(raw_guess)
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if guess == 1001:
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echo("AAAAAAGGG!")
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break
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elif guess > answer:
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echo("Too high.")
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elif guess < answer:
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echo("Too low")
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else:
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echo("Yeeeeeehaw!")
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#
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# Iteration
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#
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# Iterate with the `for` keyword
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# TODO `for` examples for strings, arrays, etc
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for elem in ["Yes", "No", "Maybe so"]:
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echo elem
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# string iterators
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let myString = """
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an example
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string to
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play with
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"""
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for line in splitLines(myString):
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echo(line)
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#
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# Procedures
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#
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type Answer = enum yes, no
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proc ask(question: string): Answer =
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echo(question, " (y/n)")
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while true:
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case readLine(stdin)
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of "y", "Y", "yes", "Yes":
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return Answer.yes # Enums can be qualified
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of "n", "N", "no", "No":
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return Answer.no
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else: echo("Please be clear: yes or no")
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proc addSugar(amount: int = 2) = # Default amount is 2, returns nothing
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for a in 1..amount:
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echo a, " sugar..."
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case ask("Would you like sugar in your tea?")
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of yes:
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addSugar(3)
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of no:
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echo "Oh do take a little!"
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addSugar()
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# No need for an `else` here. only `yes` and `no` are possible.
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```
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## Further Reading
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* [Home Page](http://nimrod-lang.org)
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* [Download](http://nimrod-lang.org/download.html)
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* [Community](http://nimrod-lang.org/community.html)
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* [FAQ](http://nimrod-lang.org/question.html)
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* [Documentation](http://nimrod-lang.org/documentation.html)
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* [Manual](http://nimrod-lang.org/manual.html)
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* [Standard Libray](http://nimrod-lang.org/lib.html)
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