Pre-RFC: Arbitrary bit-width integers

[scottmcm]

@wxblank

They would be isomorphic to () , which AFAIK is already fairly useless outside return types and generic parameters.

struct Foo; is also isomorphic to (), but is useful enough that it even has its own dedicated syntax.

I think it's useful for the same kinds of generic reasons that () is useful, and for the same kinds of reasons that [_; 0] exists as a type.

For example, u0 is the perfect always-in-bounds type for indexing a [T; 0] , the same way that u8 is the perfect always-in-bounds type for indexing a [T; 256].

@jhpratt

I know I've brought this up before, but are we certain that arbitrary bit-width integers is preferred over ranged integers

+1

I'd much rather have Integer<0..10> for indexing a [T; 10], for example.

Though there might be value in both -- I'd like Integer<A..B> + Integer<C..D> -> Integer<A+C..B+D>, but that means that Integer<0..256> would need to be a different type from u8.