RequiresContext container implementation

[sobolevn]

I would be thrilled to get your feedback, guys!

P.S. For some reason I cannot request a review from @pvldruzhinin and @theLastOfCats, but I do request it!

Closes #225
Closes #216
Closes #230
Closes #231

[theLastOfCats]

LGTM

[paveldroo]

All looks good!

[sobolevn]

TODO for later:

• support join
• add readme example
• add docs to webpage
• add API spec to webpage
• add typetests for context

[sobolevn]

I would also love to experiment with Reader that can hold both functions and values.

[sobolevn]

Didn't work. Python type system does not allow this.

[paveldroo]

Didn't work. Python type system does not allow this.

Maybe you need smth like this?

def curry(aFunction):
"""
Turns a normal python function into a curried function.

Most easily used as a decorator when defining functions:
	@curry
	def add(x, y): return x + y

"""
funcName = aFunction.__code__.co_name
numArgs = aFunction.__code__.co_argcount
def buildReader(argValues, numArgs):
	if (numArgs == 0): return aFunction(*argValues)
	else:
		return lambda x: buildReader(argValues + [x], numArgs - 1)
return Reader(buildReader([], aFunction.__code__.co_argcount))

See here: https://bitbucket.org/jason_delaat/pymonad/src/master/pymonad/Reader.py

[sobolevn]

@pvldruzhinin sorry, I didn't get your advice. How should this help me with type inference of python objects and callables?

[paveldroo]

@pvldruzhinin sorry, I didn't get your advice. How should this help me with type inference of python objects and callables?

Yeah, I have no full understanding of the problem. Just tried to find difference between our code and PyMonad implementation.
But try to look at all Reader implementation in PyMonad (edited link in previous answer), it seems they support functions and values.

[sobolevn]

Because they are untyped. Let me show where the problem is.

Current implementation:

class RequiresContext(
    BaseContainer,
    Generic[_EnvType, _ReturnType],
):

    def __init__(
        self, inner_value: Callable[[_EnvType], _ReturnType],
    ) -> None: ...

With this annotation mypy is able to infer correct types of both environment and return type.

When we change the constructor method type to def __init__(self, inner_value: _ReturnType), then we won't have any _EnvType to work with. And it will be set to <nothing>

And this is not what we want.

[paveldroo]

Ah, i see, thanks for the explanation 👌