I just read this blog post which argues that monads might be too obscure or difficult to understand as the default "interface to the impure world" in purely functional programming languages; instead, it suggests that the actor model would be more comprehensible when it comes to pedagogy. That may be true -- I do think that actors are easier to understand than monads -- but the post leaves a lot to be desired. In particular, the author offers no examples of what this sort of actor-based purely-functional language would look like, and he doesn't seem to have followed up on the blog post since it was written a few years ago.
So my question is: in what way can actors be leveraged to capture side-effects in a purely functional way? How would source code in that hypothetical language look? What advantages/disadvantages would that approach offer in comparison to monads (outside of the cosmetic differences)?