Re: functions not in type classes

Cagdas Ozgenc wrote:

You shouldn't be using multi paramater type classes in place of type constructors. Then you will have the ambiguity problems that you mention on you web site. Multi parameter type classes have the benefit of using multi dispatch based on two non related types.

Ozgenc's opinion is right. See the code below. This is a proper Haskell 98 script, tested under Hugs version December 2001. No need for multi parameter stuff. \begin{code} class Container a where celem :: Eq b => b -> a b -> Bool cmap :: (Eq b, Eq c) => (b->c) -> a b -> a c data MyList a = MyList [a] deriving Show instance Container MyList where celem x (MyList l) = elem x l cmap f (MyList l) = MyList (map f l) \end{code}