Consider the following example code: data Vector = V Float Float data Matrix = M Vector Vector liftV1 f (V x y) = V (f x) (f y) liftV2 f (V x1 y1) (V x2 y2) = V (f x1 x2) (f y1 y2) liftM1 f (M x y) = M (f x) (f y) liftM2 f (M x1 y1) (M x2 y2) = M (f x1 x2) (f y1 y2) Both pairs of lift functions have almost identical implementations. Can I merge these somehow? I know data constructors are first class values and are not types, but if I want to merge these lift functions I have to write something like lift1 f (d x y) = d (f x) (f y) lift2 f (d x1 y1) (d x2 y2) = d (f x1 x2) (f y1 y2) But this does not work, as the pattern matcher does not seem to like this. Thanks, Peter Verswyvelen PS: Of course I could define a single type like: data Pair a = P a a type Vector = Pair Float type Matrix = Pair Vector lift1 f (P x y) = P (f x) (f y) lift2 f (P x1 y1) (P x2 y2) = P (f x1 x2) (f y1 y2) But that's beside the question :)