Clean is pure and doesn't use monads. They use so called "uniqueness typing". You basicaly pass along the "world" or some part of it and the type system makes sure you do not try to "clone" the world. That is you may only do one thing to the world you have, by which you create a new world and then you make another change to the new world and so on. I haven't written anything with the monads so I can't really say, but this looks to me a bit easier to understand and use.

I don't think whether the books start with explaining how to print hello world or how to compute this or that is that important. Yes it's easier to impress the girls with something that displays a nice moving graphic than with a complex and elegant computation, but we are not in programming to impress girls are we. We'd be playing football (the europeans would play the game in which you kick the ball around all the time, americans the one in which you barely ever touch the ball with your foot. Whatever.) if that was what we were after.

A more important reason why functional languages are not used more videly is that they usualy miss useable libraries. Let's see how the implementation that do interface with the .Net world will be doing. (Not that I would mean that the .Net framework library is too useable. But still better than nothing.)