Question

Is it possible to do the following:

foo = bar
    where
        type A = (Some, Huge, Type, Sig)

        meh :: A -> (A, A) -> A

I only need to use this custom type inside the where clause, so it does not make sense to define it globally.

Answer 1

This isn’t possible. Why not just define it above the function? You don’t have to export it from the module (just use an explicit export list).

By the way, if you really do have a type that big, it’s probably a sign that you should factor it into smaller parts, especially if you have a lot of tuples as your example suggests; data-types would be more appropriate.