Idea: Trait+Impl Item for ergonomic extension traits

[scottmcm]

A somewhat related idea:

Idea: Simpler method-syntax private helpers

Reading the discussion about infix method calls made me wonder how much of the problem is that it’s just annoying to make a private helper function that uses method syntax. For example, suppose you wanted to write Vec::sorted for yourself. Today it looks something like this: trait VecEx { fn sorted(self) -> Self; } impl<T: Ord> VecEx for Vec<T> { fn sorted(mut self) -> Self { self.sort(); self } } What if, instead, you could just write this? (Note the self.) fn …

I might argue that for something as big as Itertools, the extra impl Itertools for impl Iterator {} line isn't a big deal. But for small, one-off things for local use, even the trait part is a pain, so I'd like to get right of that too.