Closes #245

Author: sobolevn

CHANGELOG.md

@@ -37,6 +37,7 @@ See [0Ver](https://0ver.org/).
 
 - Adds `Result.lift`, `Maybe.lift`, `RequiresContext.lift`,
   and `RequiresContextResult.lift` functions in addition to `IO.lift`
+- Adds
 
 
 ### Bugfixes

returns/context/requires_context.py

@@ -6,6 +6,7 @@
 
 from returns.functions import identity
 from returns.primitives.container import BaseContainer
+from returns.primitives.types import Immutable, Stateless
 
 # Context:
 _EnvType = TypeVar('_EnvType', contravariant=True)
@@ -225,7 +226,11 @@ def from_value(
 
 
 @final
-class Context(Generic[_EnvType]):
+class Context(
+    Immutable,
+    Stateless,
+    Generic[_EnvType],
+):
     """
     Helpers that can be used to work with ``RequiresContext`` container.
 

returns/context/requires_context_result.py

@@ -6,6 +6,7 @@
 
 from returns.context.requires_context import RequiresContext
 from returns.primitives.container import BaseContainer
+from returns.primitives.types import Immutable, Stateless
 from returns.result import Failure, Result, Success
 
 # Context:
@@ -648,7 +649,11 @@ def from_failure(
 
 
 @final
-class ContextResult(Generic[_EnvType]):
+class ContextResult(
+    Immutable,
+    Stateless,
+    Generic[_EnvType],
+):
     """
     Helpers that can be used to work with ``RequiresContextResult`` container.
 

returns/primitives/container.py

@@ -1,19 +1,19 @@
 # -*- coding: utf-8 -*-
 
 from abc import ABCMeta
-from typing import Any, Callable, NoReturn, TypeVar, Union
+from typing import Any, Callable, TypeVar, Union
 
 from typing_extensions import Protocol, runtime
 
-from returns.primitives.exceptions import ImmutableStateError
+from returns.primitives.types import Immutable
 
 _ValueType = TypeVar('_ValueType', covariant=True)
 _NewValueType = TypeVar('_NewValueType')
 _ErrorType = TypeVar('_ErrorType', covariant=True)
 _NewErrorType = TypeVar('_NewErrorType')
 
 
-class BaseContainer(object, metaclass=ABCMeta):
+class BaseContainer(Immutable, metaclass=ABCMeta):
     """Utility class to provide all needed magic methods to the context."""
 
     __slots__ = ('_inner_value',)
@@ -27,14 +27,6 @@ def __init__(self, inner_value) -> None:
         """
         object.__setattr__(self, '_inner_value', inner_value)  # noqa: WPS609
 
-    def __setattr__(self, attr_name: str, attr_value: Any) -> NoReturn:
-        """Makes inner state of the containers immutable."""
-        raise ImmutableStateError()
-
-    def __delattr__(self, attr_name: str) -> NoReturn:  # noqa: WPS603
-        """Makes inner state of the containers immutable."""
-        raise ImmutableStateError()
-
     def __str__(self) -> str:
         """Converts to string."""
         return '<{0}: {1}>'.format(

returns/primitives/types.py

@@ -0,0 +1,23 @@
+# -*- coding: utf-8 -*-
+
+from typing import Any, NoReturn
+
+from returns.primitives.exceptions import ImmutableStateError
+
+
+class Immutable(object):
+    """Helper type for objects that should be immutable."""
+
+    def __setattr__(self, attr_name: str, attr_value: Any) -> NoReturn:
+        """Makes inner state of the containers immutable."""
+        raise ImmutableStateError()
+
+    def __delattr__(self, attr_name: str) -> NoReturn:  # noqa: WPS603
+        """Makes inner state of the containers immutable."""
+        raise ImmutableStateError()
+
+
+class Stateless(object):
+    """Helper type for object that should be empty."""
+
+    __slots__ = ()

tests/test_context/test_requires_context/test_context.py

@@ -4,6 +4,7 @@
 
 from returns.context import Context, RequiresContext
 from returns.primitives.container import Bindable, Mappable
+from returns.primitives.exceptions import ImmutableStateError
 
 
 @pytest.mark.parametrize('container', [
@@ -20,28 +21,7 @@ def test_protocols(container, protocol):
     assert isinstance(container, protocol)
 
 
-def test_context_map():
+def test_context_immutable():
     """Ensures that RequiresContext container supports ``.map()`` method."""
-    context: RequiresContext[int, str] = RequiresContext.from_value(
-        1.0,
-    ).map(
-        str,
-    )
-    assert context(3) == RequiresContext.from_value(
-        '1.0',
-    )(RequiresContext.empty)
-
-
-def test_context_bind():
-    """Ensures that RequiresContext container supports ``.bind()`` method."""
-    def factory(number: float) -> RequiresContext[int, str]:
-        return RequiresContext(lambda deps: str(number + deps))
-
-    context: RequiresContext[int, str] = RequiresContext.from_value(
-        1.0,
-    ).bind(
-        factory,
-    )
-    assert context(3) == RequiresContext.from_value(
-        '4.0',
-    )(RequiresContext.empty)
+    with pytest.raises(ImmutableStateError):
+        Context().a = 1

tests/test_context/test_requires_context_result/test_context_result.py

@@ -11,6 +11,7 @@
     Rescueable,
     Unwrapable,
 )
+from returns.primitives.exceptions import ImmutableStateError
 from returns.result import Failure, Success
 
 
@@ -34,9 +35,7 @@ def test_protocols(container, protocol):
     assert isinstance(container, protocol)
 
 
-def test_context_map():
+def test_context_result_immutable():
     """Ensures that RequiresContext container supports ``.map()`` method."""
-    context = RequiresContextResult.from_success(1.0).map(str)
-    assert context(...) == RequiresContextResult.from_success(
-        '1.0',
-    )(RequiresContextResult.empty)
+    with pytest.raises(ImmutableStateError):
+        ContextResult().a = 1