dry-python / dry-python/returns

Mypy plugin generates incompatible type overloads for @curry decorated functions with TypeVar

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#1,071 1 comentario 0 reacciones 0 asignados Ver en GitHub
bug
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Descripción

# Bug report

## What's wrong

returns mypy plugin generate incorrect type overloads for curry decorated function with TypeVar arguments

Code to reproduce issue:
```python
from typing import TypeVar

from returns.curry import curry
from returns.io import IO

_T = TypeVar('_T', int, str)

@curry
def _union_sets(first_set: set[_T], second_set: set[_T]) -> set[_T]:
return first_set.union(second_set)

@curry
def _concat_objs(first: _T, second: _T) -> _T:
return first + second

set_1 = IO({1, 2, 3})
set_2 = IO({3, 4, 5})

union = set_1.apply(set_2.apply(IO(_union_sets)))

string_1 = IO('a')
string_2 = IO('b')

concat = string_1.apply(string_2.apply(IO(_concat_objs)))
```

Mypy gives incompatible type overloaded function error for both curried functions:
```
error: Argument 1 to "IO" has incompatible type overloaded function; expected "Callable[[Set[int]], Callable[..., Set[_T]]]" [arg-type]
error: Argument 1 to "IO" has incompatible type overloaded function; expected "Callable[[Set[int]], Callable[[Set[int]], Set[_T]]]" [arg-type]
error: Argument 1 to "IO" has incompatible type overloaded function; expected "Callable[[str], Callable[..., _T]]" [arg-type]
error: Argument 1 to "IO" has incompatible type overloaded function; expected "Callable[[str], Callable[[str], _T]]" [arg-type]
```

## How is that should be

Type overloads for functions with TypeVar's should be generated correctly

## System information

- `python` version: 3.9.7
- `returns` version: 0.16.0
- `mypy` version: 0.910

- `hypothesis` version (if any):
- `pytest` version (if any):

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