Merge pull request #180 from RyanGlScott/T178-warn-against-default-im…

…pl-of-inRange

Document that `Data.Ix.inRange` is not a suitable default for `isInRange`

src/System/Random/Internal.hs

@@ -950,7 +950,12 @@ class UniformRange a where
   --
   -- There is a default implementation of 'isInRange' via 'Generic'. Other helper function
   -- that can be used for implementing this function are `isInRangeOrd` and
-  -- `isInRangeEnum`
+  -- `isInRangeEnum`.
+  --
+  -- Note that the @isRange@ method from @Data.Ix@ is /not/ a suitable default
+  -- implementation of 'isInRange'. Unlike 'isInRange', @isRange@ is not
+  -- required to be symmetric, and many @isRange@ implementations are not
+  -- symmetric in practice.
   --
   -- @since 1.3.0
   isInRange :: (a, a) -> a -> Bool