It doesn’t really work in Scala, at least not as this article formulates it. The basic idea in Haskell is that as far as the type system is concerned, we only e

It doesn’t really work in Scala, at least not as this article formulates it. The basic idea in Haskell is that as far as the type system is concerned, we only ever compose impure actions from smaller ones. We never actually run them ourselves; the Haskell runtime does that. This means that we can pass around impure actions as values and manipulate them however we like. The Monad typeclass simply lets us write functions that are overloaded to work on many different kinds of actions, not just I/O.