[Haskell-cafe] Missing mtl classes for RWST.CPS (was: Coercing newtype-wrapped monad transformers?)

Viktor Dukhovni ietf-dane at dukhovni.org
Mon May 11 19:20:23 UTC 2020

> On May 11, 2020, at 2:30 PM, Alexis King <lexi.lambda at gmail.com> wrote:
>> I should probably mention that the reason I'm having to jump through these
>> hoops with boilerplate code is that neither "mtl", nor "transformers" provide
>> "MonadReader", "MonadWriter", "MonadState" or just "MonadRWS" instances for
> The instances are already present on master (I added them) but they have not yet been
> released to Hackage. Remarkably, mtl seems to be without a maintainer. See
> https://github.com/haskell/mtl/issues/69.

Thanks!  Good to know these are at least in the pipeline.  Perhaps some day I'll
get to trim the boilerplate down to just: "deriving instance MonadRWS".

Good luck finding someone to cut the release...


More information about the Haskell-Cafe mailing list