On Wed, Mar 25, 2015 at 10:00 AM, Norbert Melzer <timmelzer@gmail.com> wrote:

You are correct, a list is not a set. A list is a list of things, that can be there multiple times. A set is a set of things, where nothing can be twice. So take a look at Data.Set

Note that this won't actually solve the original problem; Haskell is an implementation of a strongly typed lambda calculus, not of number theory, and Haskell collections cannot (easily) contain elements of different types --- so the empty set is not an element of a set, and the empty list is not an element of a list.