[spion]

Monads being monoids isn't very interesting in a practical sense - e.g. just because you can associatively combine steps in a program isn't very interesting. (We do it all the time when we extract a subset of instructions as a procedure)

I'd say monoids are more interesting, mainly due to implications for massively parallel algorithms and caching and how finding operations that fit the laws let you reap massive benefits in both aspects.

I've yet to see something as practically interesting for monads. Perhaps monadic parsers or STM qualify. What would you say makes monads just as interesting in a practical sense?