[Haskell-cafe] Haskel let

Hi I think I've mastered much of functional programming with Haskell, or at least I can write programs which process as desired. However the existence of the "let" statement evades me apart from a quick way to define a function. Then there is the "in" and "where" parts. Its been suggested its to do with scope and is obvious. I think I need to understand it in a C/C++/Perl style of code to have a Eureka moment when it will be obvious. Can someone refer me to something which will assist me ? Andrew