Adds .rescue method, refs #274

Author: sobolevn

returns/_generated/pointfree/rescue.pyi

@@ -1,6 +1,10 @@
 from typing import Callable, TypeVar, overload
 
-from returns.context import RequiresContextIOResult, RequiresContextResult
+from returns.context import (
+    RequiresContextFutureResult,
+    RequiresContextIOResult,
+    RequiresContextResult,
+)
 from returns.future import FutureResult
 from returns.io import IOResult
 from returns.result import Result
@@ -60,6 +64,19 @@ def _rescue(
     ...
 
 
+@overload
+def _rescue(
+    function: Callable[
+        [_ErrorType],
+        RequiresContextFutureResult[_EnvType, _ValueType, _NewErrorType],
+    ],
+) -> Callable[
+    [RequiresContextFutureResult[_EnvType, _ValueType, _ErrorType]],
+    RequiresContextFutureResult[_EnvType, _ValueType, _NewErrorType],
+]:
+    ...
+
+
 @overload
 def _rescue(
     function: Callable[[_ErrorType], FutureResult[_ValueType, _NewErrorType]],

returns/context/requires_context_future_result.py

@@ -166,6 +166,60 @@ def bind(
             ),
         )
 
+    def rescue(
+        self,
+        function: Callable[
+            [_ErrorType],
+            'RequiresContextFutureResult[_EnvType, _ValueType, _NewErrorType]',
+        ],
+    ) -> 'RequiresContextFutureResult[_EnvType, _ValueType, _NewErrorType]':
+        """
+        Composes this container with a function returning the same type.
+
+        .. code:: python
+
+          >>> import anyio
+          >>> from returns.context import RequiresContextFutureResult
+          >>> from returns.future import FutureResult
+          >>> from returns.io import IOSuccess, IOFailure
+
+          >>> def rescuable(
+          ...     arg: str,
+          ... ) -> RequiresContextFutureResult[str, str, str]:
+          ...      return RequiresContextFutureResult(
+          ...          lambda deps: FutureResult.from_value(
+          ...              deps + arg,
+          ...          ) if len(arg) > 1 else FutureResult.from_failure(
+          ...              arg + deps,
+          ...          ),
+          ...      )
+
+          >>> assert anyio.run(
+          ...     RequiresContextFutureResult.from_value('a').rescue(rescuable),
+          ...     'c',
+          ... ) == IOSuccess('a')
+
+          >>> assert anyio.run(
+          ...     RequiresContextFutureResult.from_failure('a').rescue(
+          ...         rescuable,
+          ...     ),
+          ...     'c',
+          ... ) == IOFailure('ac')
+
+          >>> assert anyio.run(
+          ...     RequiresContextFutureResult.from_failure('aa').rescue(
+          ...         rescuable,
+          ...     ),
+          ...     'b',
+          ... ) == IOSuccess('baa')
+
+        """
+        return RequiresContextFutureResult(
+            lambda deps: self(deps).rescue(
+                lambda inner: function(inner)(deps),  # type: ignore
+            ),
+        )
+
     def value_or(  # noqa: WPS234
         self, default_value: _FirstType,
     ) -> Callable[

typesafety/test_context/test_requires_context_future_result/test_requires_context_future_result.yml

@@ -21,6 +21,19 @@
     reveal_type(x.bind(test))  # N: Revealed type is 'returns.context.requires_context_future_result.RequiresContextFutureResult[builtins.str, builtins.bool*, builtins.float]'
 
 
+- case: requires_context_future_result_rescue
+  disable_cache: true
+  main: |
+    from returns.context import RequiresContextFutureResult
+
+    x: RequiresContextFutureResult[str, int, float]
+
+    def test(param: float) -> RequiresContextFutureResult[str, int, bool]:
+        ...
+
+    reveal_type(x.rescue(test))  # N: Revealed type is 'returns.context.requires_context_future_result.RequiresContextFutureResult[builtins.str, builtins.int, builtins.bool*]'
+
+
 - case: requires_context_future_result_value_or
   disable_cache: true
   main: |

typesafety/test_context/test_requires_context_future_result/test_requires_context_future_result_cast.yml

@@ -0,0 +1,27 @@
+- case: requires_context_future_result_success_cast
+  disable_cache: true
+  main: |
+    from returns.context import RequiresContextFutureResult
+
+    first: RequiresContextFutureResult[str, object, Exception] = RequiresContextFutureResult.from_value(1)
+    reveal_type(first)  # N: Revealed type is 'returns.context.requires_context_future_result.RequiresContextFutureResult[builtins.str, builtins.object, builtins.Exception]'
+
+
+- case: requires_context_future_result_failure_cast
+  disable_cache: true
+  main: |
+    from returns.context import RequiresContextFutureResult
+
+    first: RequiresContextFutureResult[str, object, Exception] = RequiresContextFutureResult.from_failure(TypeError())
+    reveal_type(first)  # N: Revealed type is 'returns.context.requires_context_future_result.RequiresContextFutureResult[builtins.str, builtins.object, builtins.Exception]'
+
+
+- case: requires_context_future_result_env_cast
+  disable_cache: true
+  main: |
+    from returns.context import RequiresContextFutureResult
+
+    first: RequiresContextFutureResult[object, object, Exception]
+    second: RequiresContextFutureResult[str, object, Exception] = first
+
+    reveal_type(second)  # N: Revealed type is 'returns.context.requires_context_future_result.RequiresContextFutureResult[builtins.str, builtins.object, builtins.Exception]'

typesafety/test_context/test_requires_context_ioresult/test_requires_context_ioresult_cast.yml

@@ -0,0 +1,27 @@
+- case: requires_context_ioresult_success_cast
+  disable_cache: true
+  main: |
+    from returns.context import RequiresContextIOResult
+
+    first: RequiresContextIOResult[str, object, Exception] = RequiresContextIOResult.from_value(1)
+    reveal_type(first)  # N: Revealed type is 'returns.context.requires_context_ioresult.RequiresContextIOResult[builtins.str, builtins.object, builtins.Exception]'
+
+
+- case: requires_context_ioresult_failure_cast
+  disable_cache: true
+  main: |
+    from returns.context import RequiresContextIOResult
+
+    first: RequiresContextIOResult[str, object, Exception] = RequiresContextIOResult.from_failure(TypeError())
+    reveal_type(first)  # N: Revealed type is 'returns.context.requires_context_ioresult.RequiresContextIOResult[builtins.str, builtins.object, builtins.Exception]'
+
+
+- case: requires_context_ioresult_env_cast
+  disable_cache: true
+  main: |
+    from returns.context import RequiresContextIOResult
+
+    first: RequiresContextIOResult[object, object, Exception]
+    second: RequiresContextIOResult[str, object, Exception] = first
+
+    reveal_type(second)  # N: Revealed type is 'returns.context.requires_context_ioresult.RequiresContextIOResult[builtins.str, builtins.object, builtins.Exception]'

typesafety/test_context/test_requires_context_result/test_requires_context_cast.yml

@@ -0,0 +1,27 @@
+- case: requires_context_result_success_cast
+  disable_cache: true
+  main: |
+    from returns.context import RequiresContextResult
+
+    first: RequiresContextResult[str, object, Exception] = RequiresContextResult.from_value(1)
+    reveal_type(first)  # N: Revealed type is 'returns.context.requires_context_result.RequiresContextResult[builtins.str, builtins.object, builtins.Exception]'
+
+
+- case: requires_context_result_failure_cast
+  disable_cache: true
+  main: |
+    from returns.context import RequiresContextResult
+
+    first: RequiresContextResult[str, object, Exception] = RequiresContextResult.from_failure(TypeError())
+    reveal_type(first)  # N: Revealed type is 'returns.context.requires_context_result.RequiresContextResult[builtins.str, builtins.object, builtins.Exception]'
+
+
+- case: requires_context_result_env_cast
+  disable_cache: true
+  main: |
+    from returns.context import RequiresContextResult
+
+    first: RequiresContextResult[object, object, Exception]
+    second: RequiresContextResult[str, object, Exception] = first
+
+    reveal_type(second)  # N: Revealed type is 'returns.context.requires_context_result.RequiresContextResult[builtins.str, builtins.object, builtins.Exception]'

typesafety/test_pointfree/test_rescue.yml

@@ -46,6 +46,18 @@
     reveal_type(rescue(test))  # N: Revealed type is 'def (returns.context.requires_context_ioresult.RequiresContextIOResult[builtins.int*, builtins.float*, builtins.float*]) -> returns.context.requires_context_ioresult.RequiresContextIOResult[builtins.int*, builtins.float*, builtins.str*]'
 
 
+- case: rescue_context_future_result
+  disable_cache: true
+  main: |
+    from returns.pointfree import rescue
+    from returns.context import RequiresContextFutureResult
+
+    def test(arg: float) -> RequiresContextFutureResult[int, float, str]:
+        ...
+
+    reveal_type(rescue(test))  # N: Revealed type is 'def (returns.context.requires_context_future_result.RequiresContextFutureResult[builtins.int*, builtins.float*, builtins.float*]) -> returns.context.requires_context_future_result.RequiresContextFutureResult[builtins.int*, builtins.float*, builtins.str*]'
+
+
 - case: rescue_future_result
   disable_cache: true
   main: |

typesafety/test_result/test_result_type_cast.yml

@@ -1,4 +1,4 @@
-- case: result_success_cast
+- case: result_success_cast1
   disable_cache: true
   main: |
     from returns.result import Result, Success
@@ -7,6 +7,15 @@
     reveal_type(first)  # N: Revealed type is 'returns.result.Result[builtins.int, builtins.Exception]'
 
 
+- case: result_success_cast2
+  disable_cache: true
+  main: |
+    from returns.result import Result, Success
+
+    first: Result[object, Exception] = Success(1)
+    reveal_type(first)  # N: Revealed type is 'returns.result.Result[builtins.object, builtins.Exception]'
+
+
 - case: result_failure_cast1
   disable_cache: true
   main: |