> A type system doesn't help. So what if they're both floats? The test > is still bogus, your code will still wait too long to engage the > retro-rockets, and the billion dollar space craft will still be travelling > at hundreds of miles an hour when it reaches the surface of Mars.
A type system _could_ help. Multi-Level-Specification allows you to express physical quantities with their respective unit, and operations on them to yield the combined unit at compile-time. There are some rather complicated cases where simple unification won't solve the type-equations, but then you might annotate things explicitly. Diez -- http://mail.python.org/mailman/listinfo/python-list
