learning to love laziness

Consider the following Haskell function:

asPair x = (fst x, snd x)

This function has type forall a b. (a, b) -> (a, b) and is almost equivalent to the identity function, except it can be used to make programs terminate that might otherwise fall into a black hole. My students are extremely mystified by such functions---and I can hardly blame them! Is there a good place to read about programming with lazy evaluation that will cover such functions and when to use them? Norman