Yep[0], and if you really wanted to, you could use that syntax to express the monadic interface: putStrLn :: TheWorld -> String -> (TheWorld, ()) main ::

Yep[0], and if you really wanted to, you could use that syntax to express the monadic interface: putStrLn :: TheWorld -> String -> (TheWorld, ()) main :: TheWorld -> (TheWorld, ()) main world = (part3, ()) where (part1, _) = putStrLn world "Hello" (part2, _) = putStrLn part1 ", " (part3, _) = putStrLn part2 "world!" It would be a frustrating user experience, but it's a valid and equivalent encoding to Haskell's `IO` type. [0] I'm ignoring lazy evaluation for now, but `f` could be implemented such that it returns before `g(x)` is evaluated. This is generally not relevant for purely functional code, but it can affect performance and exception-safety.