import :std:

unit km
unit mile

# Because km and mile are not subunits
# of arith, the normal add won't match.
# But here we match and re-apply with empty
# units, then re-attach the unit in the end.
def add[u](a: int {u}, b: int {u}):
    return (a {} + b {}) {u}

def main(_):
    print(add(1 {km})(2 {km}))

# EXECUTE
# 3 km