simplemonads 1.0.9

Easy to use monads (containers) that improve the quality of your python code. Use Just to end checking for None, Success to end unhandled exceptions, Future for async, and Reader for dependencies.

simplemonads

Easy to use monads (containers) that improve the quality of your python code. Use Just to end checking for None, Success to end unhandled exceptions, Future for async, and Reader for dependencies.

Platform support

Just pip install simplemonads and you're done. You can also download this single file into your project and use it as you wish without dependencies. Works across all platforms, so CPython >= 3.5 (Windows, Linux, Mac, Android, iOS), in a single standalone html file, multiple files in the browser with dynamic loading, and even on microcontrollers with micropython!

Example GUI using monads: Success, Failure, Just, Reader, and Printer

import simplemonads as sm

try:
    from typing import Callable, Protocol, Union, Any

    class Deps(Protocol):
        "Dependencies for your application"

        def popup(self, msg) -> None:
            "Display a popup with the specified message."


    import PySimpleGUI


except:
    pass


def make(make_gui: "Callable[[],PySimpleGUI]") -> "Callable[[],Deps]":
    gui = make_gui()

    class GuiDeps:
        def popup(self, x: str):
            gui.Popup(x)

    return GuiDeps


def app(divide_by_zero: bool = False) -> sm.Reader:
    data = sm.Success(sm.Just(7))
    double = lambda x: x + (lambda y: y * 2)
    triple = lambda x: x + (lambda y: y * 3)
    result = data + triple + double

    if divide_by_zero:
        result += lambda x: x + (lambda x: x / 0)

    def effect(deps: "Deps") -> "sm.Monad":
        msg = "Answer to the Universe: "
        err = "Whoops, an error happened: "
        result | {
            sm.Success: lambda x: x | {sm.Just: lambda val: deps.popup(msg + str(val))},
            sm.Failure: lambda x: deps.popup(err + x),
        }
        return result

    return sm.Reader(effect)


@sm.run
def main():
    lib = sm.Success() + (lambda x: __import__("PySimpleGUI"))
    gui = lib | {sm.Success: lambda x: x, sm.Failure: lambda x: sm.Printer()}
    return app() + make(lambda: gui)

Handling exceptions

To demonstrate exception handling the above example can be changed to:

    return app(divide_by_zero=True) + make(lambda: gui)

This will result in safely handling the divide by zero exception and will run the following without interrupting the flow of the application:

            sm.Failure: lambda x: deps.popup(err + x),

Example monad Future

from simplemonads import Future

async def effect(data=1):
    import asyncio
    await asyncio.sleep(0.1)
    return data ** data

assert Future(2) | { Future: lambda x: x } == 2

assert Future(2) + effect | { Future: lambda x: x } == 4

assert Future(2) + effect + effect | { Future: lambda x: x } == 256

This allows easily adding async functions into the monadic pipeline. If you need special concurrency options, you can await multiple tasks from inside the effect function.