twitter/algebird — pull request #294 by jnievelt (2014-04-04 21:41:16+00:00)
Title: Adding MutableSumAll and Semigroup#bufferedSumOption,statefulSummer

Refactoring some Semigroup#sumOption optimizations to use these.

Closes #291

These should be getting test coverage indirectly, but I'm open to suggestions for additional tests to add.