Here's a patch which adds some Haddock documentation to the Control.Monad.State module. I collected examples together that I had found useful when trying to understand this module, and haddock-ized some of the comments that were already in the code. I also got permission from the original authors to include these examples.

The resulting haddock output can be seen here: http://www.syntaxpolice.org/~ijones/tmp/Control.Monad.State.html

Any comments before I commit this patch are welcome.

I think moving the examples into a separate "Examples" section on that page would be better. As it is, the examples cause too much of a gap between the data types and their constructors. Cheers, Simon