Actually, CL goes a step further, which I like: by default, integer arithmetic is arbitrary precision. There are no overflows, unless you count running out of RAM to store your numbers as an overflow. Modular arithmetic must be explicitly specified, leaving no room for surprises:

  (mod (+ x y) N)

The reason I prefer this behavior to C's is that it is more natural. Most of the time when we think of integer arithmetic, we do not assume that it is modulo N; we assume things like " x - 1 < x " will always be true. Forcing unexpected semantics on programmers is a recipe for bugs, and integer underflow/overflow bugs are not uncommon in C programs.

I think that'd probably be inappropriate for C's use cases, but I think generally it's a good move. I do like encoding the modular behavior in the type, FWIW; specifying a mod manually everywhere it goes leads to unreadable code. I agree, however, that it should probably not be the default type.

The way I see it, if you want arithmetic modulo N, you should be explicit. For example, in CL:

[Edit: Just noticed this got posted, but someone replied. The correct version of this is above.]

Sure, I don't disagree. I'm just saying that's a legitimate use case that should be supported somehow.