I'm not convinced (Bool->) is a legitimate Traversable[0], but that's at least highly concerning and makes me wish the typechecker could properly handle "Instan

I'm not convinced (Bool->) is a legitimate Traversable[0], but that's at least highly concerning and makes me wish the typechecker could properly handle "Instances should satisfy the following laws" comments as actual code. 0: in vaguely the same way that Int isn't a legitimate Monoid because you get nonsense by switching back and forth between sum and product (and min, max, xor, and, or, etc)