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 std/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 std/math

# Basic math.
assert 1 + 2 == 3        # Sum
assert 4 - 1 == 3        # Subtraction
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
assert almostEqual(PI, 3.14159265358979)
assert euclDiv(-13, -3) == 5  # Euclidean Division
assert euclMod(-13, 3) == 2   # Euclidean Modulo
import std/[strutils, strscans]

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

let (ok, year, month, day) = scanTuple("1000-01-01", "$i-$i-$i")
if ok:
  assert year == 1000
  assert month == 1
  assert day == 1
import std/[sugar, tables, sets, sequtils, strutils]

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].toHashSet

assert toSeq(1..15).mapIt(
    if it mod 15 == 0:  "FizzBuzz"
    elif it mod 5 == 0: "Buzz"
    elif it mod 3 == 0: "Fizz"
    else: $it
  ).join(" ").strip == "1 2 Fizz 4 Buzz Fizz 7 8 Fizz Buzz 11 Fizz 13 14 FizzBuzz"

Recent articles

Nim versions 2.2.0 and 2.0.10 released

The Nim Team is happy to announce two releases:

  • version 2.2.0, our new stable release
  • version 2.0.10, a patch release for Nim 2.0

Nim version 2.0.8 released

The Nim team is happy to announce Nim version 2.0.8, our fourth patch release for Nim 2.0.

Mastering Nim

The definite guide on Nim!

Written by the inventor himself.

Now with updated content for version 2.0 which solves the biggest pain point of Nim 1.0, shared memory in a multi-threaded setting.

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.