[Haskell-cafe] compiler versus interpreter

I am programming an application with a lot of interactivity. When using x<-getChar the character corresponding to the pushed key is assigned to x immediately. Launching the module through runghc works properly. However, the compiled module through ghc requires to push return after the character key in order to complete the assignation procedure. It is a bug or there is some difference between compiler an interpreter? Thanks in advance. jepalomar