[tome]

> [Monad's] motivation is purity.

This is not true and it's important to clear up this misconception lest anyone thing "the only good reason to use monads in Haskell is because it's a pure language".

* The use of monads in functional programming arose purely technically as an innovation in denotational semantics

* Then someone noticed you could use it to wrap up IO purely in Haskell

* Then it was noticed you could use it for all sorts of other stuff besides dealing with IO in a pure language.

Monads are only a little bit related to purity.

[enugu]

Yes, sure, monads, applicatives etc. have plenty of applications beyond IO, which is part of why keeping that abstraction separate from any particular use is of value.

My point is that this doesnt have much to do with static typing vs dynamic typing per se, as we dont check them statically. They are just important examples of an interface with implementations for many data types, which can be useful even in a dynamic language like Clojure. People who write a parser in a dynamic language might benefit from learning about distinction between applicatives and monads.

[tome]

Yes I agree. I just wanted to clear up a potential misconception.