Structural type hierarchy ?

[asmodehn]

Having a look at #3 it seems the main benefit compared to functools.singledispatch is the ability to work on structural types.

Therefore I wonder if one can define a hierarchy of protocols via python-typeclasses and have them checked with mypy as well ?

These days I find myself wanting to use haskell concepts in my python code (that I want to keep for the prototyping/iterative development feel) and I guess I actually want to replace nominal typing in my code with structural types + strict dynamic typing, but I am not quite sure how to go about it.

I've been wanting for a while to attempt to implement typeclasses (metaclasses were my initial take), so I'm happy to find this, thanks.

[thejohnfreeman]

You mean a hierarchy of typeclasses, e.g. the way Monad refines Applicative refines Functor in Haskell? If not that, maybe an example can help me understand what you're looking for.

[asmodehn]

Yes exactly that.
I've been wanting to do that in Python for a while to define explicit interfaces/way to use my class instances, without having traditional class inheritance getting in the way.
I've been looking for a kind of "de-facto standard" package for it without luck so far.

I believe it's called a trait in other imperative/object languages, but I haven't tried any 'traits' implementation in python just yet to know if it's actually the same or not... I know only of https://github.com/enthought/traits and https://github.com/ipython/traitlets

Thanks for any hints on that topic !