On Wed, Dec 21, 2005 at 03:47:14PM -0000, Bayley, Alistair wrote:
It's good to start with IO. Reading and writing files, parsing and printing (show and read), talking to databases, GUIs, and networking are more-or-less essential activities, and people want to know early on how to do these things. You don't have to introduce the IO monad; just tell people that we separate IO functions from "pure" functions with this special IO type, and, with the "imperative" do-notation, IO code in Haskell looks a lot like IO code in C/Java/.Net. The Really Good Stuff (real monadic programming) can come later.
I'd just add that in my opinion its handling of IO is actually one of the *strengths* of Haskell. The primary advantage Haskell has (in my mind) is that it is strongly typed, and the monadic handling of IO is an impressive display of how much that typing can clarify one's code. I'd far rather write IO code in Haskell than in any other language. Pure code can be written in any language pretty easily (albeit more easily in a functional language), since pure code doesn't have the complexities present in IO code, and it's in handling those complexities that the type-safety of Haskell really helps. -- David Roundy http://www.darcs.net