def main(field x, field y, u8 z, u8 t) -> (field[4], u8[4]) {
    field a = -y; // should parse to neg
    field b = x - y; // should parse to sub
    field c = x + - y; // should parse to add(neg)
    field d = x - + y; // should parse to sub(pos)

    u8 e = -t; // should parse to neg
    u8 f = z - t; // should parse to sub
    u8 g = z + - t; // should parse to add(neg)
    u8 h = z - + t; // should parse to sub(pos)

    assert(-0x00 == 0x00);
    assert(-0f == 0);

    return ([a, b, c, d], [e, f, g, h]);
}