[Haskell-beginners] Unwrap an expression?

Perhaps this is a dumb question, but I was pondering the whole "Lazy" aspect of Haskell, and was curious: is there someway you could create a function "M", which you could pass an expression into, so that... M (f (g... (n (x)) ...)) returns f and/or returns the inner value (g... (n (x)) ...) I don't know if that breaks the whole "referential transparency" idea or not, but with all those lambda calculus tricks I've heard about, and the lazy evaluation, I thought it would be worth asking. -- frigidcode.com theologia.indicium.us