On some platforms (like 6502) it is difficult to implement some binary operations entirely by emitting assembly. It is much easier to implement them directly in B as functions. We should provide some mechanism to let the compiler know that for *this* specific binary operation call *that* function instead.

I'm not sure about exact syntax. Could be something like this to stay consistent with __asm__ and __variadic__:

__operator__(/, div);

...

div(lhs, rhs) { ... }