Well, I was confused because getContents seems to be of type "IO String": http://www.haskell.org/ghc/docs/latest/html/libraries/base/Prelude.html#v%3AgetContent

Well, I was confused because getContents seems to be of type "IO String": http://www.haskell.org/ghc/docs/latest/html/libraries/base/Prelude.html#v%3AgetContents http://www.haskell.org/ghc/docs/latest/html/libraries/base/P... I can see why a lazy input stream could make things opaque even in a completely type-safe program, though.