simplemonads 1.0.7

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 copy the single file simplemonads/__init__.py 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 browser with Brython, and even on microcontrollers with micropython!

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

from simplemonads import Success, Failure, Just, _, Reader, run, Printer

class AppDeps:
    def __init__(self, gui=Printer()):
        self.gui = gui
     
def app(divide_by_zero=False):                      
    data = Success(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: AppDeps):
        return result | {
            Success:lambda x: x | {
                Just:lambda val: deps.gui.Popup('Answer to the Universe: ' + str(val))
            },
            Failure:lambda x: deps.gui.Popup('Whoops, an error happened: ' + x)
        } is result or result
    
    return Reader(effect)

class GuiAppDeps(AppDeps):
    def __init__(self, gui=Printer()):
        try:
            import PySimpleGUI
            self.gui = PySimpleGUI                        
        except:
            self.gui = gui
  
@run 
def main():        
    return app() + GuiAppDeps 

Handling exceptions

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

    return app(True) + GuiAppDeps

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

            Failure:lambda x: deps.gui.Popup('Whoops, an error happened: ' + 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.