Description

sobolevn

opened on Jun 24, 2020

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There's a common use-case when we need to create a type-class with several methods. Like:

class Functor(Protocol[T]):
    def map(self, function: Callable[[T], Functor[V]]) -> Functor[V]:
        ...

    @classmethod
    def from_value(cls, inner_value: V) -> Functor[V]:
        ...

Currently, there's no way we can do that.

I propose something like this:

@typeclass
class Functor(Protocol[T]):
    def map(self, function: Callable[[T], Functor[V]]) -> Functor[V]:
        ...

    @classmethod
    def from_value(cls, inner_value: V) -> Functor[V]:
        ...

I am not sure how to bound it to the actual implementation.

Activity

1. sobolevn

   added

   enhancementNew feature or requestNew feature or request

   help wantedExtra attention is neededExtra attention is needed

   on Jun 24, 2020
2. sobolevn commented on Jun 27, 2020

   

   sobolevn

   on Jun 27, 2020

   MemberAuthor

   More actions

   @Functor.instance
   class Maybe(Generic[T]):
       def map(self, function: Callable[[T], Maybe[V]]) -> Maybe[V]:
           ...
   
       @classmethod
       def from_value(cls, inner_value: V) -> Maybe[V]:
           ...
3. sobolevn commented on Jun 27, 2020

   

   sobolevn

   on Jun 27, 2020

   MemberAuthor

   More actions

   How is it different from a simple protocol?

   Reacted by Stevan Milic

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