Programming in Haskell -- an application monad for servant

I started adding an API last time and I ran into a problem where the API runs under servant's `Handler` monad but my application runs under `ReaderT ... IO`. To get the two to play nicely together I need to make my application monad more generic rather than assuming IO. This will need a bit of refactoring through the codebase but then I should be able to start serving a simple API, and hopefully also start consuming it in purescript.