Efficient, expressive, elegant

Nim is a statically typed compiled systems programming language. It combines successful concepts from mature languages like Python, Ada and Modula.

Efficient

  • Nim generates native dependency-free executables, not dependent on a virtual machine, which are small and allow easy redistribution.
  • The Nim compiler and the generated executables support all major platforms like Windows, Linux, BSD and macOS.
  • Nim's memory management is deterministic and customizable with destructors and move semantics, inspired by C++ and Rust. It is well-suited for embedded, hard-realtime systems.
  • Modern concepts like zero-overhead iterators and compile-time evaluation of user-defined functions, in combination with the preference of value-based datatypes allocated on the stack, lead to extremely performant code.
  • Support for various backends: it compiles to C, C++ or JavaScript so that Nim can be used for all backend and frontend needs.

Expressive

  • Nim is self-contained: the compiler and the standard library are implemented in Nim.
  • Nim has a powerful macro system which allows direct manipulation of the AST, offering nearly unlimited opportunities.

Elegant

  • Macros cannot change Nim's syntax because there is no need for it — the syntax is flexible enough.
  • Modern type system with local type inference, tuples, generics and sum types.
  • Statements are grouped by indentation but can span multiple lines.
import strformat

type
  Person = object
    name: string
    age: Natural # Ensures the age is positive

let people = [
  Person(name: "John", age: 45),
  Person(name: "Kate", age: 30)
]

for person in people:
  # Type-safe string interpolation,
  # evaluated at compile time.
  echo(fmt"{person.name} is {person.age} years old")


# Thanks to Nim's 'iterator' and 'yield' constructs,
# iterators are as easy to write as ordinary
# functions. They are compiled to inline loops.
iterator oddNumbers[Idx, T](a: array[Idx, T]): T =
  for x in a:
    if x mod 2 == 1:
      yield x

for odd in oddNumbers([3, 6, 9, 12, 15, 18]):
  echo odd


# Use Nim's macro system to transform a dense
# data-centric description of x86 instructions
# into lookup tables that are used by
# assemblers and JITs.
import macros, strutils

macro toLookupTable(data: static[string]): untyped =
  result = newTree(nnkBracket)
  for w in data.split(';'):
    result.add newLit(w)

const
  data = "mov;btc;cli;xor"
  opcodes = toLookupTable(data)

for o in opcodes:
  echo o
var conditional = 42

if conditional < 0:
  echo "conditional < 0"
elif conditional > 0:
  echo "conditional > 0"
else:
  echo "conditional == 0"

var ternary = if conditional == 42: true else: false

var another =
  if conditional == 0:
    "zero"
  elif conditional mod 2 == 0:
    "even"
  else:
    "odd"


# Case switch.
var letter = 'c'

case letter
of 'a':
  echo "letter is 'a'"
of 'b', 'c':
  echo "letter is 'b' or 'c'"
of 'd'..'h':
  echo "letter is between 'd' and 'h'"
else:
  echo "letter is another character"
import math

# Basic math.
assert 1 + 2 == 3        # Sum
assert 4 - 1 == 3        # Substraction
assert 2 * 2 == 4        # Multiplication
assert 4 / 2 == 2.0      # Division
assert 4 div 2 == 2      # Integer Division
assert 2 ^ 3 == 8        # Power
assert 4 mod 2 == 0      # Modulo
assert (2 xor 4) == 6    # XOR
assert (4 shr 2) == 1    # Shift Right
assert PI * 2 == TAU     # PI and TAU
assert sqrt(4.0) == 2.0  # Square Root
assert round(3.5) == 4.0 # Round
assert isPowerOfTwo(16)  # Powers of Two
assert floor(2.9) == 2.0 # Floor
assert ceil(2.9) == 3.0  # Ceil
assert cos(TAU) == 1.0   # Cosine
assert gcd(12, 8) == 4   # Greatest common divisor
assert trunc(1.75) == 1.0     # Truncate
assert floorMod(8, 3) == 2    # Floor Modulo
assert floorDiv(8, 3) == 2    # Floor Division
assert hypot(4.0, 3.0) == 5.0 # Hypotenuse
assert gamma(4.0) == 6.0      # Gamma function
assert radToDeg(TAU) == 360.0 # Radians to Degrees
assert clamp(1.4, 0.0, 1.0) == 1.0 # Clamp
import strutils

assert "con" & "cat" == "concat"
assert "    a    ".strip == "a"
assert "42".parseInt == 42
assert "3.14".parseFloat == 3.14
assert "0x666".parseHexInt == 1638
assert "TrUe".parseBool == true
assert "0o777".parseOctInt == 511
assert "a".repeat(9) == "aaaaaaaaa"
assert "abc".startsWith("ab")
assert "abc".endsWith("bc")
assert ["a", "b", "c"].join == "abc"
assert "abcd".find("c") == 2
assert "a x a y a z".count("a") == 3
assert "A__B__C".normalize == "abc"
assert "a,b".split(",") == @["a", "b"]
assert "a".center(5) == "  a  "
assert "a".indent(4) == "    a"
assert "    a".unindent(4) == "a"

for word in tokenize("This is an example"):
  echo word
import sugar, tables, sets

let variable0 = collect(newSeq):
  for item in @[-9, 1, 42, 0, -1, 9]:
    item * 2

assert variable0 == @[-18, 2, 84, 0, -2, 18]

let variable1 = collect(initTable):
  for key, value in @[0, 5, 9]:
    {key: value div 2}

assert variable1 == {0: 0, 1: 2, 2: 4}.toTable

let variable2 = collect(initHashSet):
  for item in @[-9, 1, 42, 0, -1, 9]:
    {item + item}

assert variable2 == [2, 18, 84, 0, -18, -2].toSet

Recent articles

A New Home For Our Community

Take a look at some updates to our official IRC channel as well as new ways to connect to our community via Matrix.

NimConf 2021 - Nim Online Conference

NimConf 2021 will take place in about two weeks from now -- on June 26th.

Nim in Action

The first Nim book, Nim in Action, is now available for purchase as an eBook or printed soft cover book. Learn the basics such as Nim's syntax and advanced features including macros, and gain practical experience with the language by being led through multiple application development examples.

  • Teaches the basics including the syntax of Nim.
  • Explains how to use the Nimble package manager.
  • Includes step-by-step instructions and explanations of how to develop various applications, including a chat program, a Twitter clone and more.

Support Nim

Join the 100+ companies and individuals that support Nim

The Nim project is developed globally by a group of volunteers. We welcome recurring donations, which enable us to spend more time working on Nim.

Community

Looking for the GitHub repository?

The Nim compiler and tools are all written in Nim and licensed under the MIT license, with most development taking place on GitHub. Be sure to watch the repository to get updates on Nim's development, or star it to give us some brownie points.