Re: [Haskell-cafe] how to Enumerate without lists?

Hi David, Thanks for responding. Let me re-phrase the technical question: in some hypothetical

  instance Foldable Enumerator where ...

the methods (e.g., foldMap) would be overconstrained. Is there a way to still write something like it? It seems not, as shown by these examples: Data.EnumSet cannot implement Foldable because of Enum k. http://hackage.haskell.org/package/enummapset/docs/Data-EnumSet.html Data.IntSet cannot implement Foldable because of k ~ Int. - J.