On Sat, Jun 11, 2011 at 4:21 PM, Alexander Solla <alex.solla at gmail.com> wrote: > _symmetry :: (a, a) -> (a, a) > _joinOn :: (Ord a) => (a,a) -> Set (a,a) -> Set (a,a) A note on style: we use variables starting with an underline "_" just when they are not used. This kind of use is confusing. Cheers! -- Felipe.