diff --git a/monads/list.py b/monads/list.py
index 070e7ff..2a21519 100644
--- a/monads/list.py
+++ b/monads/list.py
@@ -27,15 +27,15 @@ class List(Monad[T], Monoidal[list]):
return List([value])
def bind(self, function: Callable[[T], List[S]]) -> List[S]:
- return reduce(List.mappend, map(function, self.value), List.mzero())
+ return reduce(List.mappend, map(function, self._value), List.mzero())
def map(self, function: Callable[[T], S]) -> List[S]:
- return List(list(map(function, self.value)))
+ return List(list(map(function, self._value)))
def apply(self, functor: List[Callable[[T], S]]) -> List[S]:
return List(
- list(chain.from_iterable([map(f, self.value) for f in functor.value]))
+ list(chain.from_iterable([map(f, self._value) for f in functor._value]))
)
@classmethod
@@ -64,7 +64,7 @@ class List(Monad[T], Monoidal[list]):
return List(reduce(flat, self, List.mzero())) # type: ignore
def sort(self, key: Optional[str] = None, reverse: bool = False) -> List[T]:
- lst_copy = self.value.copy()
+ lst_copy = self._value.copy()
lst_copy.sort(key=key, reverse=reverse) # type: ignore
return List(lst_copy)
@@ -75,22 +75,22 @@ class List(Monad[T], Monoidal[list]):
functor = uncurry(cast(CurriedBinary, func))
else:
functor = func
- return reduce(functor, self.value, base_val) # type: ignore
+ return reduce(functor, self._value, base_val) # type: ignore
__and__ = lambda other, self: List.apply(self, other) # type: ignore
def mappend(self, other: List[T]) -> List[T]:
- return List(self.value + other.value)
+ return List(self._value + other._value)
__add__ = mappend
__mul__ = __rmul__ = map
__rshift__ = bind
def __sizeof__(self) -> int:
- return self.value.__sizeof__()
+ return self._value.__sizeof__()
def __len__(self) -> int:
- return len(list(self.value))
+ return len(list(self._value))
def __iter__(self) -> Iterator[T]:
- return iter(self.value)
+ return iter(self._value)
diff --git a/monads/maybe.py b/monads/maybe.py
index 9ac2e6b..c320a97 100644
--- a/monads/maybe.py
+++ b/monads/maybe.py
@@ -176,19 +176,19 @@ class First(Monoid[Maybe[T]]):
return First(Nothing())
def mappend(self, other: First):
- if isinstance(self.value, Just):
+ if isinstance(self._value, Just):
return self
else:
return other
def __repr__(self) -> str: # pragma: no cover
- return f"<First {self.value}>"
+ return f"<First {self._value}>"
__add__ = mappend
def first(xs: List[Maybe[T]]) -> Maybe[T]:
- return First.mconcat(map(lambda x: First(x), xs)).value
+ return First.mconcat(map(lambda x: First(x), xs))._value
class Last(Monoid[Maybe[T]]):
@@ -197,16 +197,16 @@ class Last(Monoid[Maybe[T]]):
return Last(Nothing())
def mappend(self, other: Last):
- if isinstance(other.value, Just):
+ if isinstance(other._value, Just):
return other
else:
return self
def __repr__(self) -> str: # pragma: no cover
- return f"<Last {self.value}>"
+ return f"<Last {self._value}>"
__add__ = mappend
def last(xs: List[Maybe[T]]) -> Maybe[T]:
- return Last.mconcat(map(lambda x: Last(x), xs)).value
+ return Last.mconcat(map(lambda x: Last(x), xs))._value
diff --git a/monads/monoid.py b/monads/monoid.py
index be85eeb..716697c 100644
--- a/monads/monoid.py
+++ b/monads/monoid.py
@@ -2,14 +2,14 @@ from __future__ import annotations
from functools import reduce
from numbers import Complex
from decimal import Decimal
-from typing import Any, Callable, Generic, Iterator, Type, TypeVar, Union
+from typing import Any, Callable, Generic, Iterator, Type, TypeVar, Union, Final
T = TypeVar("T")
class Monoid(Generic[T]):
def __init__(self, value: T) -> None:
- self.value = value
+ self._value: Final[T] = value
# FIXME: Other type set to Any, as the proper value (Monoid[T]) is
# reported as incompatible with subclass implementations due to a
@@ -29,15 +29,19 @@ class Monoid(Generic[T]):
return (
isinstance(other, Monoid)
and type(self) == type(other)
- and self.value == other.value
+ and self._value == other._value
)
__add__ = mappend
+ @property
+ def value(self) -> T:
+ return self._value
+
class Monoidal(Monoid[T]):
def __repr__(self): # pragma: no cover
- return repr(self.value)
+ return repr(self._value)
class String(Monoidal[str]):
@@ -46,7 +50,7 @@ class String(Monoidal[str]):
return cls(str())
def mappend(self, other: String) -> String:
- return String(self.value + other.value)
+ return String(self._value + other._value)
__add__ = mappend
@@ -57,7 +61,7 @@ class Addition(Monoidal[Union[int, float]]):
return cls(0)
def mappend(self, other: Addition) -> Addition:
- return Addition(self.value + other.value)
+ return Addition(self._value + other._value)
__add__ = mappend
@@ -68,6 +72,6 @@ class Multiplication(Monoidal[Union[int, float]]):
return cls(1)
def mappend(self, other: Multiplication) -> Multiplication:
- return Multiplication(self.value * other.value)
+ return Multiplication(self._value * other._value)
__add__ = mappend
diff --git a/monads/set.py b/monads/set.py
index 4bb4454..498b42b 100644
--- a/monads/set.py
+++ b/monads/set.py
@@ -38,15 +38,15 @@ class Set(Monad[T], Monoidal[set]):
return Set(unpack(value))
def bind(self, function: Callable[[T], Set[S]]) -> Set[S]:
- return reduce(Set.mappend, map(function, self.value), Set.mzero())
+ return reduce(Set.mappend, map(function, self._value), Set.mzero())
def map(self, function: Callable[[T], S]) -> Set[S]:
- return Set(set(map(function, self.value)))
+ return Set(set(map(function, self._value)))
def apply(self, functor: Set[Callable[[T], S]]) -> Set[S]:
return Set(
- set(chain.from_iterable([map(f, self.value) for f in functor.value]))
+ set(chain.from_iterable([map(f, self._value) for f in functor._value]))
)
@classmethod
@@ -75,7 +75,7 @@ class Set(Monad[T], Monoidal[set]):
return Set(reduce(flat, self, Set.mzero())) # type: ignore
def sort(self, key: Optional[str] = None, reverse: bool = False) -> Set[T]:
- lst_copy = self.value.copy()
+ lst_copy = self._value.copy()
lst_copy.sort(key=key, reverse=reverse) # type: ignore
return Set(lst_copy)
@@ -86,22 +86,22 @@ class Set(Monad[T], Monoidal[set]):
functor = uncurry(cast(CurriedBinary, func))
else:
functor = func
- return reduce(functor, self.value, base_val) # type: ignore
+ return reduce(functor, self._value, base_val) # type: ignore
__and__ = lambda other, self: Set.apply(self, other) # type: ignore
def mappend(self, other: Set[T]) -> Set[T]:
- return Set(self.value.union(other.value))
+ return Set(self._value.union(other._value))
__add__ = mappend
__mul__ = __rmul__ = map
__rshift__ = bind
def __sizeof__(self) -> int:
- return self.value.__sizeof__()
+ return self._value.__sizeof__()
def __len__(self) -> int:
- return len(set(self.value))
+ return len(set(self._value))
def __iter__(self) -> Iterator[T]:
- return iter(self.value)
+ return iter(self._value)
diff --git a/tests/test_monoids.py b/tests/test_monoids.py
index 927a11c..78161dc 100644
--- a/tests/test_monoids.py
+++ b/tests/test_monoids.py
@@ -55,3 +55,11 @@ def test_mconcat(constructor: Constructor) -> None:
c: Monoid = construct(constructor, 3)
expected: Monoid = a.mappend(b).mappend(c)
assert expected == cls.mconcat([a, b, c])
+
+
+def test_immutability(constructor: Constructor) -> None:
+ a: Monoid = construct(constructor, 1)
+ with pytest.raises(AttributeError) as excinfo:
+ # this is ignore on porpouse othewise the mypy test fail. Uncomment to check the Final check with mypy
+ a.value = 2 # type: ignore
+ assert "can't set attribute" in str(excinfo.value)