Monads in Python!

monads.py

# Monadic IO

def print_(s):
    def _():
        print s
    return _

def some_io():
    for x in ['Hello', 'World']:
        yield print_(x)
    

# Runner

def run_monad(m):
    try:
        x = next(m)
        while True:
            x = m.send(x())
    except StopIteration:
        pass


>>> run_monad(some_io())
Hello
World