Makes returns compatible with mypy 1.2 (#1588)

Author: thepabloaguilar

.github/workflows/test.yml

@@ -17,7 +17,7 @@ concurrency:
 
 jobs:
   build:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     strategy:
       fail-fast: false
       matrix:

CHANGELOG.md

@@ -8,6 +8,10 @@ See [0Ver](https://0ver.org/).
 
 ## 0.19.1 WIP
 
+### Features
+
+- Now requires `mypy>=1.2`
+
 ### Bugfixes
 
 - Fixes a problem with `do-notation` and type aliases

poetry.lock

@@ -72,13 +72,11 @@ trio = "^0.22"
 attrs = "^22.1"
 httpx = "^0.23"
 
-mypy = "^0.950"
+mypy = "^1.2.0"
 wemake-python-styleguide = "^0.17"
 flake8-pytest-style = "^1.6"
 flake8-pyi = "^22.10"
-# TODO: Remove this restriction when `ruamel.yaml.clib` works
-# correctly with Python 3.10. That lib is a dependency of `nitpick`!
-nitpick = { version = "^0.32", python = "<3.10" }
+nitpick = "^0.33.1"
 codespell = "^2.2"
 slotscheck = "^0.16.4"
 
@@ -87,7 +85,7 @@ safety = "^2.3"
 pytest = "^7.2"
 pytest-cov = "^4.0"
 pytest-randomly = "^3.12"
-pytest-mypy-plugins = "^1.9.2"
+pytest-mypy-plugins = "^1.10.1"
 pytest-subtests = "^0.9"
 hypothesis = "^6.57"
 

pyproject.toml

@@ -9,7 +9,7 @@
 def flow(
     instance: _InstanceType,
     *functions: _PipelineStepType,
-) -> _ReturnType:
+) -> _ReturnType:  # type: ignore[type-var]
     """
     Allows to compose a value and up to multiple functions that use this value.
 

returns/_internal/pipeline/flow.py

@@ -42,7 +42,7 @@
 
 
 @final
-class RequiresContext(
+class RequiresContext(  # type: ignore[type-var]
     BaseContainer,
     SupportsKind2['RequiresContext', _ReturnType, _EnvType],
     reader.ReaderBased2[_ReturnType, _EnvType],
@@ -80,7 +80,7 @@ class RequiresContext(
     __slots__ = ()
 
     #: This field has an extra 'RequiresContext' just because `mypy` needs it.
-    _inner_value: Callable[[RequiresContext, _EnvType], _ReturnType]
+    _inner_value: Callable[[_EnvType], _ReturnType]
 
     #: A convenient placeholder to call methods created by `.from_value()`:
     no_args: ClassVar[NoDeps] = object()

returns/context/requires_context.py

@@ -36,7 +36,7 @@
 
 
 @final
-class RequiresContextFutureResult(
+class RequiresContextFutureResult(  # type: ignore[type-var]
     BaseContainer,
     SupportsKind3[
         'RequiresContextFutureResult', _ValueType, _ErrorType, _EnvType,
@@ -100,10 +100,7 @@ class RequiresContextFutureResult(
     #: Inner value of `RequiresContext`
     #: is just a function that returns `FutureResult`.
     #: This field has an extra 'RequiresContext' just because `mypy` needs it.
-    _inner_value: Callable[
-        [RequiresContextFutureResult, _EnvType],
-        FutureResult[_ValueType, _ErrorType],
-    ]
+    _inner_value: Callable[[_EnvType], FutureResult[_ValueType, _ErrorType]]
 
     #: A convenient placeholder to call methods created by `.from_value()`.
     no_args: ClassVar[NoDeps] = object()

returns/context/requires_context_future_result.py

@@ -22,15 +22,15 @@
 # Result:
 _ValueType = TypeVar('_ValueType', covariant=True)
 _NewValueType = TypeVar('_NewValueType')
-_ErrorType = TypeVar('_ErrorType', covariant=True)
+_ErrorType = TypeVar('_ErrorType')
 _NewErrorType = TypeVar('_NewErrorType')
 
 # Helpers:
 _FirstType = TypeVar('_FirstType')
 
 
 @final
-class RequiresContextIOResult(
+class RequiresContextIOResult(  # type: ignore[type-var]
     BaseContainer,
     SupportsKind3['RequiresContextIOResult', _ValueType, _ErrorType, _EnvType],
     reader_ioresult.ReaderIOResultBasedN[_ValueType, _ErrorType, _EnvType],
@@ -107,10 +107,7 @@ class RequiresContextIOResult(
     #: Inner value of `RequiresContext`
     #: is just a function that returns `IOResult`.
     #: This field has an extra 'RequiresContext' just because `mypy` needs it.
-    _inner_value: Callable[
-        [RequiresContextIOResult, _EnvType],
-        IOResult[_ValueType, _ErrorType],
-    ]
+    _inner_value: Callable[[_EnvType], IOResult[_ValueType, _ErrorType]]
 
     #: A convenient placeholder to call methods created by `.from_value()`.
     no_args: ClassVar[NoDeps] = object()

returns/context/requires_context_ioresult.py

@@ -28,7 +28,7 @@
 
 
 @final
-class RequiresContextResult(
+class RequiresContextResult(  # type: ignore[type-var]
     BaseContainer,
     SupportsKind3['RequiresContextResult', _ValueType, _ErrorType, _EnvType],
     reader_result.ReaderResultBasedN[_ValueType, _ErrorType, _EnvType],
@@ -96,10 +96,7 @@ class RequiresContextResult(
     __slots__ = ()
 
     #: This field has an extra 'RequiresContext' just because `mypy` needs it.
-    _inner_value: Callable[
-        [RequiresContextResult, _EnvType],
-        Result[_ValueType, _ErrorType],
-    ]
+    _inner_value: Callable[[_EnvType], Result[_ValueType, _ErrorType]]
 
     #: A convenient placeholder to call methods created by `.from_value()`.
     no_args: ClassVar[NoDeps] = object()
@@ -337,7 +334,7 @@ def bind_context(
         """
         return RequiresContextResult(
             lambda deps: self(deps).map(
-                lambda inner: function(inner)(deps),  # type: ignore
+                lambda inner: function(inner)(deps),  # type: ignore[misc]
             ),
         )
 

returns/context/requires_context_result.py

@@ -1,6 +1,5 @@
 from typing import Iterator, List, Optional, Tuple
 
-from mypy.checker import detach_callable
 from mypy.nodes import ARG_STAR, ARG_STAR2
 from mypy.plugin import FunctionContext
 from mypy.types import CallableType, FunctionLike, Instance, Overloaded
@@ -17,6 +16,7 @@
 from returns.contrib.mypy._typeops.transform_callable import (
     Functions,
     Intermediate,
+    detach_callable,
     proper_type,
 )