pufuwozu/fantasy-land — pull request #23 by joneshf (2013-04-14 07:25:05+00:00)
Title: Monoid Identity Laws

I think these two are backwards. If I understand correctly, the left identity should be `m.zero().concat(m)` and the right identity `m.concat(m.zero())`. Those should correspond to `e * m = m` and `m * e = m` respectively.