Improves types

Author: sobolevn

.travis.yml

@@ -18,7 +18,7 @@ install:
 
 script:
   - poetry run flake8 dry_monads tests docs
-  - poetry run mypy dry_monads
+  - poetry run mypy dry_monads tests/**/*.py
   - poetry run pytest
   # TODO: add docs and enable
   # - poetry run doc8 -q docs

dry_monads/either.py

@@ -32,10 +32,7 @@ def bind(self, function) -> 'Left[ValueType]':
         """Returns the 'Left' instance that was used to call the method."""
         return Left(self._inner_value)
 
-    def value_or(
-        self,
-        default_value: NewValueType,
-    ) -> NewValueType:
+    def value_or(self, default_value: NewValueType) -> NewValueType:
         """Returns the value if we deal with 'Right' or default if 'Left'."""
         return default_value
 
@@ -73,10 +70,7 @@ def bind(
         """
         return function(self._inner_value)
 
-    def value_or(
-        self,
-        default_value: NewValueType,
-    ) -> ValueType:
+    def value_or(self, default_value: NewValueType) -> ValueType:
         """Returns the value if we deal with 'Right' or default if 'Left'."""
         return self._inner_value
 

dry_monads/primitives/monad.py

@@ -47,6 +47,11 @@ def bind(self, function):  # pragma: no cover
         """
         raise NotImplementedError
 
+    @abstractmethod
+    def value_of(self, default_value):
+        """Forces to unwrap value from monad or return a default."""
+        raise NotImplementedError
+
     def __str__(self) -> str:
         """Converts to string."""
         return '{0}: {1}'.format(

tests/test_either/test_bind.py

@@ -18,7 +18,7 @@ def factory(inner_value: int) -> Right[int]:
 def test_left_identity_failure():
     """Ensures that left identity works for Right monad."""
     def factory(inner_value: int) -> Left[TypeError]:
-        return Left(TypeError)
+        return Left(TypeError())
 
     input_value = 5
     bound = Left(input_value).bind(factory)

tests/test_primitives/test_monad.py

@@ -8,4 +8,4 @@
 def test_abstract_class():
     """Ensures that Monad can not be instanciated."""
     with pytest.raises(TypeError):
-        Monad()
+        Monad(1)  # type: ignore