Semantics of generators

[Jason Stokes]

Hi, this is kind of a novice question, but I hope it's OK to ask it here: what 
precisely is the semantics of a generator?  The Haskell report mentions them, 
but doesn't explain their semantics.  I understand how to use them in list 
comprehensions, but I don't understand how generators can be applied to 
arbitrary monads.  What does a generator applied to an arbitrary monad in a 
monad comprehension do?  How can they be used?

-- 
Jason Stokes: [EMAIL PROTECTED]