Hi,
It's true that this is the typical way of learning Haskell, but I for one think it's a bad way of learning Haskell. Very few real world programs get by without the "impure" stuff, so if you give the newbie the impression that it isn't there (by postponing it) there's a chance he'll run into a situation where he needs it before it's been even mentioned (queue newbie going "bah, academic language" and switching to C++).
I agree. It also confuses matters when the newbie is suddenly given a library of IO code to use -- but told to ignore it -- they suddenly start wondering why it is so difficult to do anything "useful" in Haskell. A consequence of which seems that the student becomes afraid (and ignorant) of Haskell.
I find that the Haskell introductions I like the most are the ones that accompany papers about STM and such. I.e. ones which have to teach the reader about the basics of Haskell IO, but doesn't have enough space to start with the pretty stuff.
I agree with this also. I don't think it is a difficult feat teaching an absolute beginner how do some some basic stuff with the IO monad. This shows straight away that haskell can do some useful stuff other than adding numbers together in Hugs.
Mix that with some actual comutations to show off some pretty stuff and you'll have a newbie who is both excited about the cool looking features of the pure aspects of Haskell, but completely aware of the fact that you can do impure stuff as well.
Yes, I wish this approach was applied much more often. Semi-related to this: I taught an algorithms and data structures class last term. In one of the classes the students were given an equation to solve and they were frantically typing it into their calculators, replacing the variable parameters with numbers. I told them they could all finish the class in 5 minutes if they used Haskell. Type the equation as it is and use higher-order functions to work out the parameters. The look of horror on the student's faces when I mentioned the 'H' word was priceless. However, they were all prepared to spend 50 minutes writing a Java program which would have the same effect. Chris.