On Fri, Mar 4, 2011 at 17:37, Chris Smith <cdsm...@gmail.com> wrote: > The most common use of Ord in real code, to be honest, is to use the value > in some data structure like Data.Set.Set or Data.Map.Map, which requires Ord > instances. For this purpose, any Ord instance that is compatible with Eq > will do fine.
It's true that you can build valid Maps and Sets with any valid instance of Ord that defines a total order that is consistent with Eq, and lookup, membership testing and insert will work. However, there are operations on Maps and Sets which make the order visible to the caller: min, max, splits, folds, etc. --Max _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
