I am trying to define a containing function to see if a value is one of the elements within a list which is polymorphic, but failed with the following codes:
> contain :: a -> [a] -> Bool
> contain x  = False
> contain x (y:ys) = if x == y then True else contain x ys
it seems that the problem is the 'operator' == does not support a polymorphic check?
Any way can solve the problem? or any alternative solution to achieve the purpose?