Nim Cheat Sheet

Practical Nim syntax covering variables, types, control flow, procedures, and sequences for a Python-like compiled language.

2 PagesIntermediateApr 15, 2026

Basics

Variables and procedures.

nim

# Variables and printinglet name = "World"          # immutablevar counter = 0               # mutableecho "Hello, ", name, "!"echo "Value: ", counterproc add(a, b: int): int =  a + b                        # implicit return of last expressionecho add(2, 3)

Types & Objects

Built-in types and a custom object type.

nim

var x: int = 42var y: float = 3.14var s: string = "text"var flag: bool = truetype  Point = object    x, y: floatvar p = Point(x: 1.0, y: 2.0)echo p.x, " ", p.y

Control Flow

Conditionals and loops.

nim

let n = 10if n > 5:  echo "big"elif n == 5:  echo "equal"else:  echo "small"for i in 0..4:  echo "i=", ivar count = 0while count < 3:  inc count

Procs & Functions

Defining and annotating procedures.

proc name(args): ReturnType = ...- Defines a procedure (function)
func- Shorthand for a proc that has no side effects
result- Implicit return variable, auto-returned at the end of a proc
discard expr- Explicitly ignores a return value
{.inline.}- Pragma requesting the compiler inline a proc
proc greet(name: string = "World")- Declares a default parameter value

Collections

Sequences, arrays, and tables.

@[1, 2, 3]- Sequence (dynamic array) literal
[1, 2, 3]- Fixed-size array literal
{"a": 1, "b": 2}.toTable- Creates a hash table
seq[int]- Sequence type holding ints
for x in mySeq: echo x- Iterates a sequence
mySeq.add(4)- Appends an element to a sequence

Pro Tip

Nim compiles to C and lets you drop into low-level control with pragmas or ptr types for hot loops, while keeping high-level, Python-like syntax everywhere else.

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