ekmett/lens — pull request #9 by sjoerdvisscher (2012-08-06 15:04:17+00:00)
Title: Restricting Representables to functors that are also Traversable.

This is not really a pull request, more a pull suggestion.

Most representable functors are also traversable, so the class is more useful if `rep` is lifted to `repA :: Applicative g => (Rep f -> g a) -> g (f a)`. This excludes some representable functors, most notably `(->) e`, but in the lens package that instance isn't that useful anyway.