Zig Functools

A Zig library that provides functional programming tools such as map, reduce and filter.

Add it to your project

Add the .functools dependency to your build.zig.zon.

$ zig fetch --save git+https://github.com/ali-shahwali/zig-functools

Add this to your build.zig inside the build function.

const functools = b.dependency("functools", .{
        .target = target,
        .optimize = optimize,
    });
exe.root_module.addImport("functools", functools.module("functools"));
// Or, if you are building a library
// lib.root_module.addImport("functools", functools.module("functools"));

The library can now be imported as a module.

const functools = @import("functools");

Examples

The documentation contains some examples. The tests are also good examples of how to use the library, below are some simple examples from the tests.

Map over slice and increment each element.

test "test map mutable slice on i32 slice without args" {
    const allocator = testing.allocator;

    var slice = try range.rangeSlice(allocator, i32, 3);
    defer allocator.free(slice);

    map(mappers.inc(i32), slice);

    try testing.expectEqualSlices(i32, slice, &[_]i32{ 1, 2, 3 });
}

Filter even integers.

test "test filter on i32 slice" {
    const allocator = testing.allocator;
    const slice = try rangeSlice(allocator, i32, 6);
    defer allocator.free(slice);
    const even = try filter(
        allocator,
        predicates.even(i32),
        slice,
    );
    defer allocator.free(even);

    try testing.expectEqualSlices(i32, even, &[_]i32{ 0, 2, 4 });
}

Check that every vector is orthogonal to the x basis vector.

const Point2D = struct {
    x: i32,
    y: i32,
};

fn orthogonal(p2: Point2D) fn (Point2D) bool {
    return (struct {
        fn e(p1: Point2D) bool {
            return (p1.x * p2.x + p1.y * p2.y) == 0;
        }
    }).e;
}

test "test every on Point2D slice" {
    const allocator = testing.allocator;
    const slice = try allocator.alloc(Point2D, 3);
    @memcpy(slice, &[_]Point2D{
        .{ .x = 0, .y = 1 },
        .{ .x = 0, .y = 3 },
        // This one is not orthogonal to (1, 0)
        .{ .x = 1, .y = 4 },
    });
    defer allocator.free(slice);

    const e_x = Point2D{ .x = 1, .y = 0 };
    const every_orthogonal = every(orthogonal(e_x), slice);

    try testing.expect(!every_orthogonal);
}