Functions

Functions

Functions use def. Parameter types are required. Return type annotations are optional.

def add(a: Int, b: Int) -> Int {
    return a + b
}

def greet(name: Str, greeting: Str = "Hello") -> None {
    print(f"{greeting}, {name}!")
}

greet("Alice")
greet("Bob", greeting="Hi")   # named argument

The pure modifier marks a function as side-effect-free. Pure functions can only call other pure functions:

pure def double(x: Int) -> Int {
    return x * 2
}

Lambdas

Anonymous functions with 0, 1, or 2 parameters:

let double = lambda x: Int: x * 2
let add = lambda a: Int, b: Int: a + b
print(double(21))       # 42

Lambdas capture variables from the enclosing scope:

def make_adder(n: Int) -> (Int) -> Int {
    return lambda x: Int: x + n
}

let add5 = make_adder(5)
print(add5(10))         # 15

Operators

Arithmetic

Comparison

==, !=, <, >, <=, >= work on numbers, strings, and data types.

Containment

Works on List, Set, Dict (tests keys), and Str (substring test).

Logical

and, or, not. Short-circuit evaluation.

Assignment

+=, -=, *=, /=, |= (set union in place).