Platform-Specific Code

How platform code works

Tape abstracts platform differences through the runtime library. Each target has its own runtime (rt/win64/, rt/uusi/, rt/linux/) that implements standard library modules like io. User code imports these modules without knowing which platform implementation backs them.

import io from "io";   // resolved to platform-specific runtime at link time
io.println("works everywhere");

@link directive

Declares a native library dependency:

@link("user32");
extern fn MessageBoxA(hwnd: *u8, text: *u8, caption: *u8, flags: u32) -> i32;

On Windows, this links against user32.dll. On Uusi, it links the corresponding .sto.

Available targets

Conditional compilation

For code that must differ per platform within a single module, use if inside a @tape {} block:

@tape {
    if (TARGET == "win64") {
        @emit fn get_ticks() -> u64 { return GetTickCount() as u64; }
    } else {
        @emit fn get_ticks() -> u64 { return sys.ticks(); }
    }
}

Link modules

For complex FFI boundaries, use a dedicated link module:

@link("opengl32");

pub extern fn glClear(mask: u32);
pub extern fn glClearColor(r: f32, g: f32, b: f32, a: f32);
pub extern fn glViewport(x: i32, y: i32, w: i32, h: i32);

Other modules import this to access the extern functions without repeating @link.

Last modified: 2026-05-27 20:22:46 UTC