conal/Boolean — pull request #10 by rhymoid (2014-06-21 15:53:56+00:00)
Title: Added impliesB to Boolean, defaults for true and notB

When writing the defaults, I stuck to (at most) minimal logic. Unfortunately, this means I can't write a default, and the new class would break old code. It's quite a downside, but the lack of `implies` (or a symbolic version) in the Prelude is a bit annoying by itself.