High Order Function with Type Parameter

[shelby3]

@troiganto

I think this reply hits the nail on the head. What you want are types, not traits.Traits are always implemented on different types...

Data types are not extensible.

@troiganto

...to stay with your example, there is only one correct way to implement Pos and Nat. Thus, there isn't even any need to define them as traits.

That would mean u32, u8, u16 are all the same type Positive.

It seems perhaps you are misunderstanding why we need interfaces. We need interfaces so we can compose with shared attributes and behaviors that can apply to different data types.