extern fn printf(format: [*:0]const u8, ...) c_int; extern fn strlen(str: [*:0]const u8) usize; const msg = "Hello, world!\n"; pub export fn main(argc: c_int, argv: **u8) c_int { _ = argv; _ = argc; if (printf(msg) != @as(c_int, @intCast(strlen(msg)))) return -1; return 0; }