{-# RULES
"map/map"    forall f g xs.  map f (map g xs) = map (f.g) xs
"map/append" forall f xs ys. map f (xs ++ ys) = map f xs ++ map f ys
  #-}

{-# RULES
"map"       [~1] forall f xs.   map f xs                = build (\c n -> foldr (mapFB c f) n xs)
"mapList"   [1]  forall f.      foldr (mapFB (:) f) []  = map f
"mapFB"     forall c f g.       mapFB (mapFB c f) g     = mapFB c (f.g)
  #-}

{-# RULES
  "map/map" [~2]  forall f g xs.
    map f (map g xs) = map (f.g) xs; "f" op True y = False;
    "g" op True y = False
#-}