Closes #254

Author: sobolevn

CHANGELOG.md

@@ -23,6 +23,7 @@ See [0Ver](https://0ver.org/).
 
 - Adds `RequiresContextResult` container
 - Adds `RequiresContextResultE` alias
+- Adds `ReaderResult` and `ReaderResultE` aliases
   for `RequiresContextResult[..., ..., Exception]`
 - Adds `RequiresContextResult` support for `bind` and `rescue`
 - Adds `RequiresContextResult` support for `flatten`
@@ -37,6 +38,7 @@ See [0Ver](https://0ver.org/).
 
 - Adds `RequiresContextIOResult` container
 - Adds `RequiresContextIOResultE` alias
+- Adds `ReaderIOResult` and `ReaderIOResultE` aliases
   for `RequiresContextIOResult[..., ..., Exception]`
 - Adds `RequiresContextIOResult` support for `bind` and `rescue`
 - Adds `RequiresContextIOResult` support for `flatten`

docs/pages/context.rst

@@ -306,6 +306,32 @@ Use it when you work with impure context-related functions that might fail.
 This is basically **the main type** that is going to be used in most apps.
 
 
+Aliases
+-------
+
+There are several useful alises for ``RequiresContext``
+and friends with some common values:
+
+- :attr:`returns.context.requires_context_result.ReaderResult`
+  is an alias for ``RequiresContextResult[...]`` to save you some typing.
+  Uses ``Reader`` because it is a native name for this concept from Haskell.
+- :attr:`returns.result.requires_context.ReaderResultE`
+  is an alias for ``RequiresContextResult[..., Exception]``,
+  just use it when you want to work with ``RequiresContextResult`` containers
+  that use exceptions as error type.
+  It is named ``ResultE`` because it is ``ResultException``
+  and ``ResultError`` at the same time.
+- :attr:`returns.context.requires_context_io_result.ReaderIOResult`
+  is an alias for ``RequiresContextIOResult[...]`` to save you some typing.
+  Uses ``Reader`` because it is a native name for this concept from Haskell.
+- :attr:`returns.result.requires_context.ReaderIOResultE`
+  is an alias for ``RequiresContextIOResult[..., Exception]``,
+  just use it when you want to work with ``RequiresContextIOResult`` containers
+  that use exceptions as error type.
+  It is named ``ResultE`` because it is ``ResultException``
+  and ``ResultError`` at the same time.
+
+
 FAQ
 ---
 

returns/context/__init__.py

@@ -14,9 +14,13 @@
     ContextResult as ContextResult,
     RequiresContextResult as RequiresContextResult,
     RequiresContextResultE as RequiresContextResultE,
+    ReaderResult as ReaderResult,
+    ReaderResultE as ReaderResultE,
 )
 from returns.context.requires_context_io_result import (  # noqa: F401
     ContextIOResult as ContextIOResult,
     RequiresContextIOResult as RequiresContextIOResult,
     RequiresContextIOResultE as RequiresContextIOResultE,
+    ReaderIOResult as ReaderIOResult,
+    ReaderIOResultE as ReaderIOResultE,
 )

returns/context/requires_context_io_result.py

@@ -981,3 +981,9 @@ def ask(cls) -> RequiresContextIOResult[_EnvType, _EnvType, Any]:
 RequiresContextIOResultE = RequiresContextIOResult[
     _EnvType, _ValueType, Exception,
 ]
+
+#: Alias to save you some typing. Uses original name from Haskell.
+ReaderIOResult = RequiresContextIOResult[_EnvType, _ValueType, _ErrorType]
+
+#: Alias to save you some typing. Uses ``Exception`` as error type.
+ReaderIOResultE = RequiresContextIOResult[_EnvType, _ValueType, Exception]

returns/context/requires_context_result.py

@@ -714,3 +714,9 @@ def ask(cls) -> RequiresContextResult[_EnvType, _EnvType, Any]:
 RequiresContextResultE = RequiresContextResult[
     _EnvType, _ValueType, Exception,
 ]
+
+#: Alias to save you some typing. Uses original name from Haskell.
+ReaderResult = RequiresContextResult[_EnvType, _ValueType, _ErrorType]
+
+#: Alias to save you some typing. Has ``Exception`` as error type.
+ReaderResultE = RequiresContextResult[_EnvType, _ValueType, Exception]

tests/test_context/test_requires_context_io_result/test_requires_context_io_result_cast.py

@@ -1,6 +1,11 @@
 # -*- coding: utf-8 -*-
 
-from returns.context import RequiresContextIOResult, RequiresContextIOResultE
+from returns.context import (
+    ReaderIOResult,
+    ReaderIOResultE,
+    RequiresContextIOResult,
+    RequiresContextIOResultE,
+)
 
 
 def _function(arg: int) -> RequiresContextIOResultE[int, float]:
@@ -12,6 +17,19 @@ def _function(arg: int) -> RequiresContextIOResultE[int, float]:
 
 
 def test_requires_context_io_resulte():
-    """Ensures that RequiresContextResultE correctly typecast."""
+    """Ensures that RequiresContextIOResultE correctly typecast."""
     container: RequiresContextIOResult[int, float, Exception] = _function(1)
     assert container(0) == RequiresContextIOResult.from_success(10.0)(0)
+
+
+def test_requires_context_io_aliases():
+    """Ensures that ReaderIOResult correctly typecast."""
+    container: ReaderIOResultE[int, float] = _function(1)
+    container2: ReaderIOResult[int, float, Exception] = _function(1)
+    container3: ReaderIOResultE[int, float] = ReaderIOResultE.from_success(
+        10.0,
+    )
+    container4: ReaderIOResultE[int, float] = ReaderIOResult.from_success(10.0)
+
+    assert container(0) == container2(0) == container3(0) == container4(0)
+    assert container(0) == RequiresContextIOResult.from_success(10.0)(0)

tests/test_context/test_requires_context_result/test_requires_context_result_cast.py

@@ -1,6 +1,11 @@
 # -*- coding: utf-8 -*-
 
-from returns.context import RequiresContextResult, RequiresContextResultE
+from returns.context import (
+    ReaderResult,
+    ReaderResultE,
+    RequiresContextResult,
+    RequiresContextResultE,
+)
 
 
 def _function(arg: int) -> RequiresContextResultE[int, float]:
@@ -15,3 +20,16 @@ def test_requires_context_resulte():
     """Ensures that RequiresContextResultE correctly typecast."""
     container: RequiresContextResult[int, float, Exception] = _function(1)
     assert container(0) == RequiresContextResult.from_success(10.0)(0)
+
+
+def test_requires_context_aliases():
+    """Ensures that ReaderResult correctly typecast."""
+    container: ReaderResultE[int, float] = _function(1)
+    container2: ReaderResult[int, float, Exception] = _function(1)
+    container3: ReaderResultE[int, float] = ReaderResultE.from_success(
+        10.0,
+    )
+    container4: ReaderResultE[int, float] = ReaderResult.from_success(10.0)
+
+    assert container(0) == container2(0) == container3(0) == container4(0)
+    assert container(0) == RequiresContextResult.from_success(10.0)(0)