[ANN] Release Candidate for `mtl-2.3`

Hello all,

Chessai and I are excited to announce a release candidate for mtl: mtl-2.3-rc3!


The timeline for release will be as follows:

  • This announcement marks the start of the timeline

  • We will give 2 weeks of testing before considering release

  • If no major issues are filed before then, mtl-2.3-rc3 will be released as mtl-2.3, and if issues are found, they will be amended, and a new release candidate will be announced, resetting the 2 week period.

To test mtl-2.3-rc3 for yourself, please feel free to add the following to your cabal.project:

  type: git
  location: https://github.com/haskell/mtl.git 
  tag: 5d0f62b8007bb96e49f36a5544741cfe96a97130

or, if you’re a stack user add this entry to your extra-deps:

- git: https://github.com/haskell/mtl.git
  commit: 5d0f62b8007bb96e49f36a5544741cfe96a97130

And make sure to adjust all bounds/allow-newer accordingly. Please note that this release of mtl is a full major version release, and will be the last of the 2.x series before work begins on updating the mtl class hierarchy.


  • Add instances for Control.Monad.Trans.Writer.CPS and Control.Monad.Trans.RWS.CPS from transformers 0.5.6 and add Control.Monad.Writer.CPS and Control.Monad.RWS.CPS.

  • Control.Monad.Cont now re-exports evalCont and evalContT

  • Add tryError, withError, handleError, and mapError to

Control.Monad.Error.Class, and re-export from Control.Monad.Except.

  • Remove Control.Monad.List and Control.Monad.Error

  • Remove instances of deprecated ListT and ErrorT

  • Remove re-exports of Error

  • Add instances for Control.Monad.Trans.Accum and [Control.Monad.Trans.Select](http://control.monad.trans.select/)

  • Remove re-exports of Control.Monad, Control.Monad.Fix and Data.Monoid modules

I’d like to thank the many contributors who offered patches, tickets, and other help in the preparation of this release. We appreciate all of your help!

Happy hacking!



Does not resolve. Anything interesting in there? :smiley:

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Ah shoot the formatting got screwed up. I think it was inserted or something.

please release this.

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Seems like there are handful of issues…