Type

A type in the Zig language is a special data type that refers to other data types. It's a comptime-only type.

As function arguments

Functions that accept type as arguments cannot be exported by Zigar:

const std = @import("std");

pub const Uint32 = u32;

pub fn printTypeName(comptime T: type) void {
    std.debug.print("{s}\n", .{@typeName(T)});
}

import { printTypeName, Uint32 } from './type-example-1.zig';

printTypeName(Uint32);

import { printTypeName, Uint32 } from './type-example-1.zig';
         ^^^^^^^^^^^^^
SyntaxError: The requested module './type-example-1.zig' does not provide an export named 'printTypeName'

Used in constant declarations

Constants of the type type can be exported:

pub const Int32 = i32;
pub const FatalError = error{ ate_expired_doritos, thought_cat_was_pillow };
pub const PizzaTopping = enum { pine_apple, anchovy, baked_beans, pierogi };
pub const Point = struct { x: f32, y: f32 };

import { FatalError, Int32, PizzaTopping, Point } from './type-example-2.zig';

console.log(new Int32(1234).valueOf())
console.log(new Point({ x: 0.5, y: 0.7 }).valueOf());
for (const [ name, item ] of PizzaTopping) {
    console.log(`${item}`);
}
for (const [ name, error ] of FatalError) {
    console.log(`${error}`);
}

1234
{ x: 0.5, y: 0.699999988079071 }
pine_apple
anchovy
baked_beans
pierogi
Error: Ate expired doritos
Error: Thought cat was pillow

In anonymous structs

Types stored in anonymous structs can also be exported:

pub const SmallIntegers = .{
    .u1 = u1,
    .u2 = u2,
    .u3 = u3,
    .u4 = u4,
    .u5 = u5,
    .u6 = u6,
    .u7 = u7,
};

import { SmallIntegers } from './type-example-3.zig';

console.log(new SmallIntegers.u2(3).valueOf());

3

As comptime fields

Comptime fields can be of the type type:

fn Point(comptime T: type) {
    return struct {
        x: T,
        y: T,
        comptime Type: type = T,
    };
};
pub const PointI32 = Point(i32);
pub const PointI64 = Point(i64);
pub const PointF32 = Point(f32);
pub const PointF64 = Point(f64);

import { PointI32, PointI64 } from './type-example-4.zig';

const p1 = new PointI32({ x: 45, y: -12 });
console.log(p1.Type.name, p1.valueOf());
const p2 = new PointI64({ x: 45, y: -12 });
console.log(p2.Type.name, p2.valueOf());

i32 { x: 45, y: -12, Type: {} }
i64 { x: 45n, y: -12n, Type: {} }