(I hope this question is on-topic -- I tried searching for an answer but didn't find a definitive answer. If this happens to be off-topic or already answered, please moderate/remove it.)
I remember having heard/read the half-joking comment about Haskell being the best imperative language a few times, which of course sounds weird as Haskell is usually best known for its functional features.
So my question is, what qualities/features (if any) of Haskell give reason to justify Haskell being deemed the best imperative language -- or is it actually more of a joke?