Nick Name wrote:
This approach is called "monads" and is needed because haskell is a lazy language, so order of evaluation is unspecified, while input/output usually needs a precise order of evaluation.
It is needed because Haskell is a functional language, where functions are referentially transparent, so the result of applying a function to an argument depends only upon the function and the argument, and not upon some hidden "state". Even if Haskell were strict, you still wouldn't be able to treat I/O operations as functions without discarding referential transparency.
Maybe someone has to suggest some simple article on monads.
"What the hell are Monads?" http://www.dcs.gla.ac.uk/~nww/Monad.html -- Glynn Clements <glynn.clements@virgin.net>