scalaz/scalaz — pull request #174 by seanparsons (2012-10-19 14:00:20+00:00)
Title: Tiny optimisation to the Semigroup for Map.

Inside the append method the second parameter (which is call by name) is actually used twice, once to check the size and the second time to assign it to either from or to. I just added in a val that eagerly consumes the call by name parameter and used that instead.