Functions and generics

Function declarations

fun add(left: i32, right: i32) -> i32 {
    return left + right;
}

fun log(message: str) {
    println("{}", message);
}

Parameters use name: type. Functions that return a value use -> type; omitting the return type defines a value-less function.

return

fun choose(flag: bool) -> i32 {
    if (flag) {
        return 1;
    }
    return 0;
}

A value-less function can use return;.

Generic functions

fun identity<T>(value: T) -> T {
    return value;
}

fun main() {
    var integer: i32 = identity<i32>(10);
    var decimal: f64 = identity<f64>(3.14);
}

Generic calls require explicit type arguments. Calling a generic template as identity(10) without type arguments produces an error.

Generic structs

struct Pair<A, B> {
    first: A;
    second: B;
}

fun main() {
    var pair: Pair<i32, f64> = Pair<i32, f64> {
        first: 1,
        second: 2.5
    };
}

Each concrete type combination produces a specialized function or struct definition.

Default parameters

Default parameters use integer, floating-point, or string literals. A call can omit a trailing argument when its parameter declares a default value.

fun repeat(value: i32, count: i32 = 1) -> i32 {
    return value * count;
}

var result: i32 = repeat(7);

Generic rules

• Generic function calls require explicit type arguments.
• Functions exposed through export(...) cannot be generic.
• ptr<T> and array<T, N> are built-in memory types, not user-defined generic templates.