-- ** The \"@By@\" operations
-- | By convention, overloaded functions have a non-overloaded
-- counterpart whose name is suffixed with \`@By@\'.
+ --
+ -- It is often convenient to use these functions together with
+ -- 'Data.Function.on', for instance @'sortBy' ('compare'
+ -- \`on\` 'fst')@.
-- *** User-supplied equality (replacing an @Eq@ context)
-- | The predicate is assumed to define an equivalence.