Greetings Haskell community, This is my first ever post so please be gentle... Here's where I got to: Jumped into GHCi: GHCi, version 7.0.3: http://www.haskell.org/ghc/ :? for help Loading package ghc-prim ... linking ... done. Loading package integer-gmp ... linking ... done. Loading package base ... linking ... done. Defined my function: Prelude> let rightTriangles = [ (a,b,c) | c <- [1..10], b <- [1..10], a <- [1..10], a^2 + b^2 == c^2 ] Tested my function: Prelude> rightTriangles [(4,3,5),(3,4,5),(8,6,10),(6,8,10)] Now, I want to define a refinement of this that will only select values whose total is 24. I could write it so: let rightTriangles = [ (a,b,c) | c <- [1..10], b <- [1..10], a <- [1..10], a^2 + b^2 == c^2,* a+b+c == 24*] However, it seems like a bit of a waste if I already have "rightTriangles" defined. I tried a few things, but none of them worked: Prelude> let rightTriangles` = rightTriangles, a+b+c == 24 <interactive>:1:21: parse error on input `=' Prelude> let rightTriangles` = rightTriangles | a+b+c == 24 <interactive>:1:21: parse error on input `=' Prelude> let rightTriangles` = [rightTriangles, a+b+c == 24] <interactive>:1:21: parse error on input `=' Prelude> let rightTriangles` = [rightTriangles | a+b+c == 24] <interactive>:1:21: parse error on input `=' Basically, I'm trying to work out how to draw data from a list already to hand. Alexander