[Haskell-cafe] How to fold on types?

Say I have things like: data LongDec = LongDef a b c ... x y z values = [ 'a', 'b', 'c', ... 'x', 'y', 'z' ] Now I want them to be "LongDef 'a' 'b' 'c' ... 'x' 'y' 'z'". In form, this is something like folding. But since the type changes, so code like following won't work: foldl (\def value -> def value) LongDef values Is it possible to do this in some way? -- 竹密岂妨流水过 山高哪阻野云飞 And for G+, please use magiclouds#gmail.com.