Cats: Missing functions for RWST

[LukaJCB]

We're currently missing listen from Writer and local from Reader.

Here's an easy implementation:

def listen[A](fa: ReaderWriterStateT[M, E, L, S, A]): ReaderWriterStateT[M, E, L, S, (A, L)] =
  ReaderWriterStateT((e, s) => fa.run(e, s).map {
    case (l, s, a) => (l, s, (a, l))
  })

def local[A](f: E => E)(fa: ReaderWriterStateT[M, E, L, S, A]): ReaderWriterStateT[M, E, L, S, A] =
  ReaderWriterStateT((e, s) => fa.run(f(e), s))

[kubukoz]

You're spoiling the fun with these easy implementations!

[LukaJCB]

Speaking of listen, we should add that one to WriterT as well:

def listen[A, L](w: WriterT[F, L, A]): WriterT[F, L, (A, L)] =
    WriterT(F.map(w.run) {
      case (l, a) => (l, a -> l)
    })

[calvinbrown085]

Hi @LukaJCB I wouldn't mind picking this one up.

[YuvalItzchakov]

@calvinbrown085 Did you end up working on this?

[calvinbrown085]

@YuvalItzchakov I have not yet, I have not found the time! If someone else would like to pick this up please feel free!

[kun-song]

@calvinbrown085 so I will take it :)

[CucumisSativus]

Hey @satansk are you still working on it? If not would you mind me taking it from you?

[kun-song]

@CucumisSativus I almost forget about this issue, but I will continue to work on this :)

[CucumisSativus]

@satansk so, good luck with it! :)

[wojciechUrbanski]

Hey @satansk, are You working on that issue? If not, can I take it?

[kun-song]

@wojciechUrbanski go ahead, it's yours :)

[barambani]

Happy to add it if no one is doing it.

[barambani]

This can be closed now. Thanks.