Well, in this simple example it is trivial to do the same by wrapping statements in a closure, but it's a bit more nuanced than that. But you still can't assign

Well, in this simple example it is trivial to do the same by wrapping statements in a closure, but it's a bit more nuanced than that. But you still can't assign a for-loop as a value to a variable, for example (to exaggerate a little). This becomes more apparent when using monads for non-IO applications like parsing. It's difficult (but not impossible, of course) to implement things like backtracking or non-determinism by writing lots of closures in an imperative programming language, they don't compose as nicely. There are parser combinator libraries (similar to Parsec) done in other languages of course, but some of them even implement monads in the language they work in. I recall seeing "class Monad" written in Python, I think it was in the pyparsec library.