The new States library is really a new implementation of Effects. It works in pretty much the same way, but emphasising the thing that the Effects library is best at and fixing some of its shortcomings.

There are two main differences at the moment:

- Everything has to be labelled - There's no 'implicit' lifting of smaller sets of states

The first is annoying for things like Console IO, so I might change that. The second means that we have a much better chance of providing decent error messages, one day.