[Haskell-beginners] reverse 'lookup'

Hi, The lookup function can locate something in a a-list: lookup :: Eq a => a -> [(a,b)] -> Maybe b is there an easy way to do a reverse lookup: rlookup :: Eq b => b -> [(a,b)] -> Maybe a or perhaps a builtin function to flip a pair: (a, b) -> (b, a) Thanks, Patrick -- ===================== Patrick LeBoutillier Rosemère, Québec, Canada