> This is yet another "monad" that can't do the list monad, > and is not therefore actually a monad. The function passed > to bind may be called zero times

> This is yet another "monad" that can't do the list monad, > and is not therefore actually a monad. The function passed > to bind may be called zero times, once, or n times. (Or > perhaps rather, any number of times, but I think phrasing > it this way underscores the place where many putative > monads fall down.) The author's implementation support lists just fine -- Monad is just a typeclass, which can be emulated using Python's inheritance. Unfortunately dynamic typing makes the code much uglier than in Haskell, but that's to be expected. class List(Monad): def __init__(self, items): self.__items = list(items) def __str__(self): return str(self.__items) def bind(self, func): items = [] for ii in map(func, self.__items): items.extend(ii.__items) return List(items) print List([1, 2, 3, 4]) >> (lambda x: List([x * x]))