Re: [Haskell-cafe] Code Golf

ghci> let diag = foldr (curry (prod mappend fst snd . uncurry (coprod mappend (splitAt 2) (splitAt 1)))) []

nice :) thanks to the comments of Martijn and Jan we can replace prod and coprod by liftA2 and <fancy dots>:

let diag = foldr (curry (liftA2 mappend fst snd.uncurry (((flip.). (((.).).).(.)) mappend (splitAt 2) (splitAt 1)))) []

It works for the finite tests but, unfortunately, not for the infinite one :(

take 10 $ diag [[ (m,n) | n <- [1..]] | m <- [1..]] *** Exception: stack overflow