Make Option covariant (#190)

* Make Option covariant

* Use a separate covariant out type

* Fixed Result covariance

Author: dbrattli

README.md

@@ -9,7 +9,7 @@
 > Pragmatic functional programming
 
 Expression aims to be a solid, type-safe, pragmatic, and high performance
-library for frictionless and practical functional programming in Python 3.11+.
+library for frictionless and practical functional programming in Python 3.10+.
 
 By pragmatic, we mean that the goal of the library is to use simple abstractions
 to enable you to do practical and productive functional programming in Python
@@ -57,7 +57,7 @@ similar to Python, but F# can also do a lot of things better than Python:
 ## Getting Started
 
 You can install the latest `expression` from PyPI by running `pip` (or
-`pip3`). Note that `expression` only works for Python 3.11+.
+`pip3`). Note that `expression` only works for Python 3.10+.
 
 ```console
 > pip install expression
@@ -88,7 +88,7 @@ To add Pydantic v2 support, install the `pydantic` extra:
   functions and methods.
 - Support PEP 634 and structural pattern matching.
 - Code must pass strict static type checking by
-  [pylance](https://devblogs.microsoft.com/python/announcing-pylance-fast-feature-rich-language-support-for-python-in-visual-studio-code/).
+  [Pylance](https://devblogs.microsoft.com/python/announcing-pylance-fast-feature-rich-language-support-for-python-in-visual-studio-code/).
   Pylance is awesome, use it!
 - [Pydantic](https://pydantic-docs.helpmanual.io/) friendly data types. Use Expression
   types as part of your Pydantic data model and (de)serialize to/from JSON.
@@ -325,7 +325,6 @@ The map2 function allows us to achieve this behavior. It takes two Option values
 
 This approach ensures that our combined value reflects the presence or absence of data in the original Options.
 
-
 ```python
 from expression import Some, Nothing, Option
 from operator import add

expression/core/compose.py

@@ -17,7 +17,6 @@
 _J = TypeVar("_J")
 
 _P = TypeVarTuple("_P")
-_Q = TypeVarTuple("_Q")
 _X = TypeVarTuple("_X")
 _Y = TypeVarTuple("_Y")
 _Z = TypeVarTuple("_Z")
@@ -41,70 +40,76 @@ def compose(__fn1: Callable[[_A], _B], __fn2: Callable[[_B], _C], __fn3: Callabl
 
 @overload
 def compose(
-    __fn1: Callable[[_A], _B],
-    __fn2: Callable[[_B], _C],
-    __fn3: Callable[[_C], _D],
-    __fn4: Callable[[_D], _E],
+    fn1: Callable[[_A], _B],
+    fn2: Callable[[_B], _C],
+    fn3: Callable[[_C], _D],
+    fn4: Callable[[_D], _E],
+    /,
 ) -> Callable[[_A], _E]: ...
 
 
 @overload
 def compose(
-    __fn1: Callable[[_A], _B],
-    __fn2: Callable[[_B], _C],
-    __fn3: Callable[[_C], _D],
-    __fn4: Callable[[_D], _E],
-    __fn5: Callable[[_E], _F],
+    fn1: Callable[[_A], _B],
+    fn2: Callable[[_B], _C],
+    fn3: Callable[[_C], _D],
+    fn4: Callable[[_D], _E],
+    fn5: Callable[[_E], _F],
+    /,
 ) -> Callable[[_A], _F]: ...
 
 
 @overload
 def compose(
-    __fn1: Callable[[_A], _B],
-    __fn2: Callable[[_B], _C],
-    __fn3: Callable[[_C], _D],
-    __fn4: Callable[[_D], _E],
-    __fn5: Callable[[_E], _F],
-    __fn6: Callable[[_F], _G],
+    fn1: Callable[[_A], _B],
+    fn2: Callable[[_B], _C],
+    fn3: Callable[[_C], _D],
+    fn4: Callable[[_D], _E],
+    fn5: Callable[[_E], _F],
+    fn6: Callable[[_F], _G],
+    /,
 ) -> Callable[[_A], _G]: ...
 
 
 @overload
 def compose(
-    __fn1: Callable[[_A], _B],
-    __fn2: Callable[[_B], _C],
-    __fn3: Callable[[_C], _D],
-    __fn4: Callable[[_D], _E],
-    __fn5: Callable[[_E], _F],
-    __fn6: Callable[[_F], _G],
-    __fn7: Callable[[_G], _H],
+    fn1: Callable[[_A], _B],
+    fn2: Callable[[_B], _C],
+    fn3: Callable[[_C], _D],
+    fn4: Callable[[_D], _E],
+    fn5: Callable[[_E], _F],
+    fn6: Callable[[_F], _G],
+    fn7: Callable[[_G], _H],
+    /,
 ) -> Callable[[_A], _H]: ...
 
 
 @overload
 def compose(
-    __fn1: Callable[[_A], _B],
-    __fn2: Callable[[_B], _C],
-    __fn3: Callable[[_C], _D],
-    __fn4: Callable[[_D], _E],
-    __fn5: Callable[[_E], _F],
-    __fn6: Callable[[_F], _G],
-    __fn7: Callable[[_G], _H],
-    __fn8: Callable[[_H], _T],
+    fn1: Callable[[_A], _B],
+    fn2: Callable[[_B], _C],
+    fn3: Callable[[_C], _D],
+    fn4: Callable[[_D], _E],
+    fn5: Callable[[_E], _F],
+    fn6: Callable[[_F], _G],
+    fn7: Callable[[_G], _H],
+    fn8: Callable[[_H], _T],
+    /,
 ) -> Callable[[_A], _T]: ...
 
 
 @overload
 def compose(
-    __fn1: Callable[[_A], _B],
-    __fn2: Callable[[_B], _C],
-    __fn3: Callable[[_C], _D],
-    __fn4: Callable[[_D], _E],
-    __fn5: Callable[[_E], _F],
-    __fn6: Callable[[_F], _G],
-    __fn7: Callable[[_G], _H],
-    __fn8: Callable[[_H], _T],
-    __fn9: Callable[[_T], _J],
+    fn1: Callable[[_A], _B],
+    fn2: Callable[[_B], _C],
+    fn3: Callable[[_C], _D],
+    fn4: Callable[[_D], _E],
+    fn5: Callable[[_E], _F],
+    fn6: Callable[[_F], _G],
+    fn7: Callable[[_G], _H],
+    fn8: Callable[[_H], _T],
+    fn9: Callable[[_T], _J],
+    /,
 ) -> Callable[[_A], _J]: ...
 
 
@@ -141,29 +146,31 @@ def starcompose() -> Callable[[Any], Any]: ...
 
 
 @overload
-def starcompose(__fn1: Callable[[Unpack[_P]], _A]) -> Callable[[Unpack[_P]], _A]: ...
+def starcompose(fn1: Callable[[Unpack[_P]], _A], /) -> Callable[[Unpack[_P]], _A]: ...
 
 
 @overload
 def starcompose(
-    __fn1: Callable[[Unpack[_P]], tuple[Unpack[_Y]]], __fn2: Callable[[Unpack[_Y]], _B]
+    fn1: Callable[[Unpack[_P]], tuple[Unpack[_Y]]], fn2: Callable[[Unpack[_Y]], _B], /
 ) -> Callable[[Unpack[_P]], _B]: ...
 
 
 @overload
 def starcompose(
-    __fn1: Callable[[Unpack[_P]], tuple[Unpack[_Y]]],
-    __fn2: Callable[[Unpack[_Y]], tuple[Unpack[_Z]]],
-    __fn3: Callable[[Unpack[_Z]], _C],
+    fn1: Callable[[Unpack[_P]], tuple[Unpack[_Y]]],
+    fn2: Callable[[Unpack[_Y]], tuple[Unpack[_Z]]],
+    fn3: Callable[[Unpack[_Z]], _C],
+    /,
 ) -> Callable[[Unpack[_P]], _C]: ...
 
 
 @overload
 def starcompose(
-    __fn1: Callable[[Unpack[_P]], tuple[Unpack[_Y]]],
-    __fn2: Callable[[Unpack[_Y]], tuple[Unpack[_Z]]],
-    __fn3: Callable[[Unpack[_Z]], tuple[Unpack[_X]]],
-    __fn4: Callable[[Unpack[_X]], _D],
+    fn1: Callable[[Unpack[_P]], tuple[Unpack[_Y]]],
+    fn2: Callable[[Unpack[_Y]], tuple[Unpack[_Z]]],
+    fn3: Callable[[Unpack[_Z]], tuple[Unpack[_X]]],
+    fn4: Callable[[Unpack[_X]], _D],
+    /,
 ) -> Callable[[Unpack[_P]], _D]: ...