Hi Thanks. A light bulb just went on :). I am still in awe of how much "special syntax" is made of such simple base. Haskell certainly is an interesting thing to learn, its like fractals, complexity and beuty from simplicity. S ----Original Message Follows---- Crypt Master, CM> I have noticed that lists seem to swtich between CM> using [] and using (). for example: CM> CM> listSum [] = 0 CM> listSum (x:xs) = x + listsum xs The parentheses are just 'normal' parentheses that are needed because application binds stronger than (:). Without the parentheses, you would get listSum x : xs which is the same as (listSum x) : xs . HTH, Stefan _________________________________________________________________ MSN 8 helps eliminate e-mail viruses. Get 2 months FREE*. http://join.msn.com/?page=features/virus