Move MonadRandom instances so they are no longer orphans

[andrewthad]

Since MonadRandom is an mtl style typeclass and this library depends on transformers, it seems like it should provide the usual pass through instances. Things like:

instance MonadRandom m => MonadRandom (ReaderT r m) where ...

Is there a reason these were omitted, or would you take a PR for this?

[byorgey]

But the library does provide these instances. For example, the one you mention is here:

https://github.com/byorgey/MonadRandom/blob/master/Control/Monad/Random.hs#L182

Did you encounter a situation where these did not work for you?

[andrewthad]

Ah, it looks like there are two problems. One is that I was trying to use the pass through instance for ListT, which doesn't exist. That's fine though because people shouldn't really use ListT anyway. The second problem is that these instances are all defined as orphans, and so they don't show up in the haddocks. I've actually run into this issue in both text-show and in aeson recently. There might be a haddock fix for this at some point in the future. In this case, it seems like the instances could just be moved to the Class module so that they would not longer be orphans.

[byorgey]

Ah, yes, making them non-orphans so they show up in the Haddocks is a good idea. Would you be willing to make a PR for that?

[andrewthad]

Yeah.

[byorgey]

Thanks! I'll leave this issue open with a different title.

[andrewthad]

PR is up.