Yes, but are there any effects systems in use outside of maybe Haskell? Effects seem mostly to be stuck in the research lab and have been for a long time.
Verse has effects, which by virtue of exposing it to the entire Fortnite community probably makes it a bigger language than Haskell in terms of user counts.
I don't mean "effects" in the sense where you can have effect handlers which get delimited continuations and all; it'd just mark what could happen (like checked exceptions). But I can't think of any languages with that and not effect handlers; Koka, Eff, and Unison come to mind for effects, though their practical-ness may vary.
