Haskell's IO monad actually has excellent exception support, including async exceptions and masking them in critical sections. There are `Maybe` and `Either` a

Haskell's IO monad actually has excellent exception support, including async exceptions and masking them in critical sections. There are `Maybe` and `Either` and they're great at streamlining error handling in pure code, but when it comes to IO most libraries just throw exceptions (including the standard library).