Types

Vow has no null. Optional and fallible values use Option and Result from the prelude.

Primitives and collections

Type	Notes
`int`	Default integer width on the native path
`int64`	Wider integer; no implicit mix with `int` — use `as`
`f32` / `f64`	Floats + casts (`phase2_collections.vow`)
`bool`	`true` / `false`
`String`	Heap string; `len(s)`, concat, trim/replace/split/join
`Array<T>`	Index, `.len()`, `array_push`, index assign, `for x in xs`
`Map<String, V>`	String keys only (v1); `map_new` / `map_get` / `map_set` / `len`

// fragment-only
let wide = n as int64;
let ratio = 0.5 as f64;

Structs, enums, match

class ≡ struct. Enums construct with Shape::Circle(2); match patterns use bare variants (Circle(r), not Shape::Circle(r)). Matches must be exhaustive.

Single inheritance ships: open class / extends / mandatory override (inheritance.vow). Dispatch is static.

Interfaces — static and dyn

// fragment-only
fn total_area(shapes: Array<dyn Shape>) -> int {
    var sum = 0;
    for s in shapes {
        sum = sum + s.area();
    }
    return sum;
}

Static interface parameters are monomorphized. Heterogeneous collections use dyn Interface + vtables (tests/lang/dyn_shapes.vow in a repo clone).

Type aliases, function values, lambdas

// fragment-only
type Score = int;

fn double(x: int) -> int { return x * 2; }

let ys = array_map(xs, double);
let zs = array_map(xs, (x: int) -> x * 3);
let evens = array_filter(xs, is_even);

Capability types

Opaque: FsRead, FsWrite, Net, Env, Clock, Rand, Proc, Threads, and the bundle Caps.

Next

OOP — classes, interfaces, inheritance, chaining
Errors and Option
Syntax