Agreed. Clear, real examples of abstract ideas are really important, and applies to much more than just monads. RWH's monads stuff (in particular its parsec cha

Agreed. Clear, real examples of abstract ideas are really important, and applies to much more than just monads. RWH's monads stuff (in particular its parsec chapter) is a good example of a concept in action, and its easy to see why you would actually use that model. Some 'first principles' things are difficult to present like this because there are usually better ways to do it. The state monad is like this. Even in haskell there are more expressive (and easier to use) tools to do the same thing. In this case i think we can all accept somewhat ad hoc examples as long as they are disclaimed.