membership

[haskell-request]

Original-Via: uk.ac.st-and.cs; Wed, 13 Nov 91 16:58:45 GMT

The operator which was called `in` in version 1.0 seems to have
vanished without trace since `in` became a reservedid. Can I suggest
it be restored to PreludeList, possibly with the name `contains`:

contains :: (Eq a) => [a] -> a -> Bool
[]     `contains` x             = False
(y:ys) `contains` x | x==y      = True
                    | otherwise = ys `contains` x