The Direct module exposes way too much

[David Feuer]

I think it's pretty weird that Direct.Par derives a MonadReader Sched instance. It's also pretty weird that Direct exposes the Sched type despite not offering any documentation of it or any functions for working with it. I think it probably makes sense to remove that instance and require users to import DirectInternal to get the Sched type.

[Simon Marlow]

Agreed, and I definitely support efforts to clean up and document the API here.