[jeremyjh]

I agree there isn't a lot written that explains this but I have inferred and used the following pattern. I build a massive monad tower that includes the different things I need like a reader with configuration data, a resourcet process monad, a logging writer etc. However I rarely use that monad in my signatures, I generally use a more restricted type class. For example I have a ConfigReader type class that does exactly and only what you would expect. I have a typeclass for writing to the database, for call distributed process, etc. Now because some of those require MonadIO I do end up with a lot of code that could theoretically do any IO. That could be restricted at the cost of creating more and richer typelcass interfaces myself but I do not think it is necessary for the most part.