twitter/scalding — pull request #51 by johnynek (2012-04-05 18:31:48+00:00)
Title: Feature/headfix

previously, head/last could not be used together, and they didn't work with map-side aggregation (For instance, the use-case of getting any particular element from a grouping without concern as to which). Using head/last forced everything onto the reducers.

This implementation uses reduce, so it's clear how it fits into our usual methods.