Support trait bounds on instance functions ... about dora HOT 3 CLOSED

I would propose implementing Rust's solution using where T: X for now since it seems to be the easiest and least intrusive to implement. We already have quite some use cases for this feature and switching later when we have the right design should be quite simple.

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I agree with going the where T : X route – I have come to the conclusion that methods which cannot be available for the class as-is (because they have additional constraints), should live in traits and impls (which carry that additional constraint), not in the class/struct (syntax might be wrong, but it hopefully clarifies the approach):

trait Sort[T] where T : Sortable {
  fun sort ...
}

impl Sort[T] for List[T] {
  fun sort ...
}

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I have around 4 pages of notes and different designs on this, and I think none of them were good enough in the end.

For now, such methods have to be defined on traits, which I guess is ok in many cases.

I'll just close this (and maybe add some wiki page in the future that sums up the discussion here as well as the additional notes).

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