scalaz/scalaz — pull request #470 by gpampara (2013-08-13 08:16:55+00:00)
Title: Reuse ==>> instances if possible.

The `Tip` constructor is often pattern matched against and can just be used as the
return value instead of using a value constructor. Also, favor the use of
`empty` over `Tip()`.

Signed-off-by: Gary Pamparà