[Haskell-cafe] Replacing [a] with (Set c a) in Monad instance.

Hello. Given: newtype Dist a = D {unD :: [(a,Int)]} instance Monad Dist where return x = D [(x,1)] d >>= f = D [(y,q*p) | (x,p) <- unD d, (y,q) <- unD (f x)] fail _ = D [] How would one change Dist to wrap an instance of the (Data.Edison.Set c a) typeclass so that the Monad instance could be implemented in terms of e.g. singleton, unionWith, empty, etc? Thanks Daniel