Description

sobolevn

opened on Jun 20, 2021

Issue body actions

We need to be sure that classes and returns can be used together and that typing works.

Plan:

1. Install returns as dev-dependency
2. Create special typesafety/test_integration/test_returns folder where we would test it
3. In pytest-mypy-plugins we would need to add returns_plugin to mypy settings

Activity

1. sobolevn

   added

   enhancementNew feature or requestNew feature or request

   on Jun 20, 2021
2. sobolevn commented on Jun 20, 2021

   

   sobolevn

   on Jun 20, 2021

   MemberAuthor

   More actions

   We would probably would need to improve https://classes.readthedocs.io/en/latest/pages/dry-python.html page as well.
3. thepabloaguilar

   self-assigned this

   on Oct 2, 2021
4. thepabloaguilar commented on Oct 2, 2021

   

   thepabloaguilar

   on Oct 2, 2021

   Member

   More actions

   Could you say more about what those tests should be, please?
5. sobolevn commented on Oct 2, 2021

   

   sobolevn

   on Oct 2, 2021

   MemberAuthor

   More actions

   We need to test:

   1. Result.success_type and failure_type
   2. Maybe with empty
   3. IOResult

   So, imagine that you want to dispatch some action based on the result/mayb type using classes. That's we basically need to cover for different types.
6. thepabloaguilar commented on Oct 3, 2021

   

   thepabloaguilar

   on Oct 3, 2021

   Member

   More actions

   I got some errors with Result using the example from the docs:

   from classes import typeclass
   from returns.result import Result, Success, Failure
   
   @typeclass
   def result_to_str(instance) -> str:
       """This is a typeclass definition to convert Result container to str."""
   
   @result_to_str.instance(Result.success_type)
   def _result_to_str_success(instance: Result) -> str:
       return str(instance.unwrap())  # will always receive `Success` types
   
   @result_to_str.instance(Result.failure_type)
   def _result_to_str_failure(instance: Result) -> str:
       return str(instance.failure())  # will always receive `Failure` types
   
   if __name__ == '__main__':
       result_to_str(Success('test'))
       result_to_str(Failure('test'))

   mypy output:

   ex.py:10: error: Instance "returns.result.Result[Any, Any]" does not match inferred type "Type[returns.result._Success[Any]]"
   ex.py:16: error: Instance "returns.result.Result[Any, Any]" does not match inferred type "Type[returns.result._Failure[Any]]"
   ex.py:23: error: Argument 1 to "result_to_str" has incompatible type "Result[str, Any]"; expected <nothing>
   ex.py:24: error: Argument 1 to "result_to_str" has incompatible type "Result[Any, str]"; expected <nothing>
   Found 4 errors in 1 file (checked 1 source file)
   

   PS.: I'm using the returns plugin too
7. thepabloaguilar commented on Oct 3, 2021

   

   thepabloaguilar

   on Oct 3, 2021

   Member

   More actions

   The same thing for Maybe 😢

   from classes import typeclass
   from returns.maybe import Maybe, Some, Nothing
   
   @typeclass
   def maybe_to_str(instance) -> str:
       """This is a typeclass definition to convert Maybe container to str."""
   
   @maybe_to_str.instance(Maybe.success_type)
   def _maybe_to_str(instance: Maybe) -> str:
       return str(instance.unwrap())  # will always receive `Maybe` types
   
   @maybe_to_str.instance(Maybe.failure_type)
   def _nothing_to_str(instance: Maybe) -> str:
       return str(instance)  # will always receive `Nothing`
   
   if __name__ == '__main__':
       maybe_to_str(Some('test'))
       maybe_to_str(Nothing)

   mypy output:

   ex.py:10: error: Instance "returns.maybe.Maybe[Any]" does not match inferred type "Type[returns.maybe._Some[Any]]"
   ex.py:15: error: Instance "returns.maybe.Maybe[Any]" does not match inferred type "Type[returns.maybe._Nothing]"
   ex.py:21: error: Argument 1 to "maybe_to_str" has incompatible type "Maybe[str]"; expected <nothing>
   ex.py:22: error: Argument 1 to "maybe_to_str" has incompatible type "Maybe[NoReturn]"; expected <nothing>
   Found 4 errors in 1 file (checked 1 source file)
   
8. sobolevn commented on Oct 3, 2021

   

   sobolevn

   on Oct 3, 2021

   MemberAuthor

   More actions

   @thepabloaguilar Will you have the time to debug why this happens?
9. thepabloaguilar commented on Oct 3, 2021

   

   thepabloaguilar

   on Oct 3, 2021

   Member

   More actions

   I can try, it's a problem with classes mypy plugin
10. thepabloaguilar commented on Oct 4, 2021

    

    thepabloaguilar

    on Oct 4, 2021

    Member

    More actions

    How do you develop mypy plugin locally? I want to put some breakpoints 😄
11. sobolevn commented on Oct 4, 2021

    

    sobolevn

    on Oct 4, 2021

    MemberAuthor

    More actions

    Try --pdb option for mypy. I don't use debuggers, sorry.

Issue actions