Crate assert_bound

When working with iterators/futures or other hign-generic types sometimes it's useful to assert that type of some expression implements some traits or even cast smt to impl Trait.

This crate provides macros for both goals — assert_bound and as_opaque.

Macros

as_opaque	Cast type to opaque type that implements trait(s) (impl Trait + Trait2)
assert_bound	Assert that expression implements trait(s) at compile-time.