First steps

Variables

var declares a mutable binding; let is reserved for pattern- binding (covered later). Annotate the type, or let the checker infer it from the initialiser.

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Numbers have sizes

There’s no untyped int. The eight integer types are i8, i16, i32, i64 (signed) and u8, u16, u32, u64 (unsigned), plus usize for native pointer-width counts. Two floats: f32 and f64. Mixing widths needs an explicit cast.

var a: i32 = 7;
var b: i64 = a as i64;   // narrow → wide cast
var c: i32 = b as i32;   // wide → narrow (may truncate)

Control flow

if / else, while, and three-part for.

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if is also an expression, for one-line ternaries.

var max: i32 = if (a > b) { a } else { b };

Functions

function add(a: i32, b: i32): i32 {
    return a + b;
}

Return and parameter types are always required — even void for procedures. There’s no inference at the signature boundary.

Next: Types →