-isIn _msg x ys = elem__ x ys
-isn'tIn _msg x ys = notElem__ x ys
-
---these are here to be SPECIALIZEd (automagically)
-elem__ :: Eq a => a -> [a] -> Bool
-elem__ _ [] = False
-elem__ x (y:ys) = x == y || elem__ x ys
-
-notElem__ :: Eq a => a -> [a] -> Bool
-notElem__ _ [] = True
-notElem__ x (y:ys) = x /= y && notElem__ x ys