[Haskell-beginners] Understanding Haskell fcn calls

[blackcat at pro-ns.net]

When I learn a new language, I like to look at the assembly code for 
some simple fcn calls.  I tried GHC -S on the following program:

    add' x y = x + y

    main = do
       print $ add' 1 2


The result of  ghc -S add.hs  was 301 lines of assembly code. Adding 
an explicit type annotation for add' brought it down to 252 lines, and 
the code was still beyond my meager ability to take in assembly.

Is there a good reference that gives a simple explanation of how 
Haskell function calls work?  This seems crucial to understanding how 
to efficiently use the language, given what I've read about tail call 
optimization.

thanks
Lee Short