# \[ANN\] Release Candidate for \`mtl-2.3\`

**URL:** <https://discourse.haskell.org/t/ann-release-candidate-for-mtl-2-3/3687>\
**Category:** Announcements\
**Created:** [November 19, 2021, 12:38am UTC](https://discourse.haskell.org/t/ann-release-candidate-for-mtl-2-3/3687 "2021-11-19T00:38:23Z")\
**Posts on this page:** 5\
**Page:** 1

<div class="post-metadata">

**Author:** ![emilypi](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.haskell.org/emilypi/32/5307_2.png) [@emilypi](https://discourse.haskell.org/u/emilypi)\
**Post date:** [November 19, 2021, 12:38am UTC](https://discourse.haskell.org/t/ann-release-candidate-for-mtl-2-3/3687/1 "2021-11-19T00:38:23Z")

</div>

Hello all,

Chessai and I are excited to announce a release candidate for `mtl`: [`mtl-2.3-rc3`](https://github.com/haskell/mtl/releases/tag/v2.3-rc3)!

## Timeline

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`:

```haskell

source-repository-package
  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`:

```haskell

- 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_.

## Changelog

- 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!

Emily

---

<div class="post-metadata">

**Author:** ![wiz](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.haskell.org/wiz/32/2408_2.png) [@wiz](https://discourse.haskell.org/u/wiz)\
**Post date:** [November 19, 2021, 11:26am UTC](https://discourse.haskell.org/t/ann-release-candidate-for-mtl-2-3/3687/2 "2021-11-19T11:26:28Z")

</div>

> [@emilypi](#):
>
> [http://control.monad.trans.select/](http://control.monad.trans.select/)

Does not resolve. Anything interesting in there? 😃

---

<div class="post-metadata">

**Author:** ![emilypi](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.haskell.org/emilypi/32/5307_2.png) [@emilypi](https://discourse.haskell.org/u/emilypi)\
**Post date:** [November 19, 2021, 3:26pm UTC](https://discourse.haskell.org/t/ann-release-candidate-for-mtl-2-3/3687/3 "2021-11-19T15:26:02Z")

</div>

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

---

<div class="post-metadata">

**Author:** ![rednaZ](https://avatars.discourse-cdn.com/v4/letter/r/4bbf92/32.png) [@rednaZ](https://discourse.haskell.org/u/rednaZ)\
**Post date:** [March 2, 2022, 8:25pm UTC](https://discourse.haskell.org/t/ann-release-candidate-for-mtl-2-3/3687/4 "2022-03-02T20:25:27Z")

</div>

please release this.

---

<div class="post-metadata">

**Author:** ![Abab9579](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.haskell.org/abab9579/32/2163_2.png) [@Abab9579](https://discourse.haskell.org/u/Abab9579)\
**Post date:** [March 4, 2022, 4:18am UTC](https://discourse.haskell.org/t/ann-release-candidate-for-mtl-2-3/3687/5 "2022-03-04T04:18:37Z")

</div>

Seems like there are handful of issues…

> <https://github.com/haskell/mtl/issues/101>
>
> Here are some build errors that I've noticed:
> 
> \`HsYAML\`:
> 
> \`\`\`
> src/Data/YAML…/Loader.hs:60:30: error:
> Not in scope: type constructor or class ‘MonadFix’
> Perhaps you meant ‘MonadFail’ (imported from Util)
> |
> 60 | decodeLoader :: forall n m . MonadFix m =\> Loader m n -\> BS.L.ByteString -\> m (Either (YE.Pos, String) \[n\])
> | ^^^^^^^^
> 
> src/Data/YAML/Loader.hs:159:29: error:
> Not in scope: type constructor or class ‘MonadFix’
> Perhaps you meant ‘MonadFail’ (imported from Util)
> |
> 159 | , MonadFix
> | ^^^^^^^^
> 
> \`\`\`
> 
> \`algebraic-graphs\`:
> 
> \`\`\`
> src/Algebra/Graph/NonEmpty.hs:690:93: error:
> • Variable not in scope:
> liftM2
> :: (a1 -\> b1 -\> (a1, b1))
> -\> NonEmpty (a, a) -\> NonEmpty (b, b) -\> NonEmpty ((a, a), (b, b))
> • Perhaps you meant ‘lift’ (imported from Control.Monad.State)
> |
> 690 | appendNonEmpty (fmap (\\((a1,a2),(b1,b2)) -\> ((a1, b1), \[(a1, b2), (a2, b1)\])) $ liftM2 (,) ipxs' ipys') $
> | ^^^^^^
> 
> src/Algebra/Graph/NonEmpty.hs:713:7: error:
> • Variable not in scope:
> liftM2
> :: (a0 -\> b0 -\> (a0, b0))
> -\> NonEmpty (a, a) -\> NonEmpty (b, b) -\> NonEmpty ((a, a), (b, b))
> • Perhaps you meant ‘lift’ (imported from Control.Monad.State)
> |
> 713 | $ liftM2 (,) (pairs1 xs) (pairs1 ys)
> | ^^^^^^
> \`\`\`
> 
> \`happy\`:
> 
> \`\`\`
> src/Grammar.lhs:470:27: error:
> Variable not in scope: when :: Bool -\> M () -\> t
> |
> 470 | \> checkArity x = when (x \> arity) $ addErr (show x++" out of range")
> | ^^^^
> \`\`\`
> 
> \`lucid\`:
> 
> \`\`\`
> src/Lucid/Base.hs:164:10: error:
> Not in scope: type constructor or class ‘MonadFix’
> Perhaps you meant ‘MonadFail’ (imported from Prelude)
> |
> 164 | instance MonadFix m =\> MonadFix (HtmlT m) where
> | ^^^^^^^^
> 
> src/Lucid/Base.hs:195:23: error:
> Not in scope: type constructor or class ‘MonadIO’
> Perhaps you meant ‘Monad’ (imported from Prelude)
> |
> 195 | instance MonadIO m =\> MonadIO (HtmlT m) where
> | ^^^^^^^
> \`\`\`
> 
> \`regex-tdfa\`:
> 
> \`\`\`
> lib/Text/Regex/TDFA/CorePattern.hs:207:34: error:
> • Variable not in scope:
> liftM2 :: (a1 -\> a1 -\> a1) -\> Maybe Int -\> Maybe Int -\> Maybe Int
> • Perhaps you meant ‘lift’ (imported from Control.Monad.RWS)
> |
> 207 | seqTake (x1,y1) (x2,y2) = (x1+x2,liftM2 (+) y1 y2)
> | ^^^^^^
> 
> lib/Text/Regex/TDFA/CorePattern.hs:468:39: error:
> • Variable not in scope:
> replicateM
> :: Int
> -\> PM HandleTag
> -\> RWST
> (Maybe GroupIndex)
> \[Either Tag GroupInfo\]
> (\[OP\] -\> \[OP\], Tag)
> Data.Functor.Identity.Identity
> \[HandleTag\]
> • Perhaps you meant ‘replicate’ (imported from Prelude)
> |
> 468 | bs \<- fmap (++\[bAdvice\]) $ replicateM (pred $ length branches) newUniq -- 2 \<= length ps
> | ^^^^^^^^^^
> 
> lib/Text/Regex/TDFA/CorePattern.hs:470:18: error:
> Variable not in scope:
> forM
> :: \[(Pattern, HandleTag)\]
> -\> ((Pattern, HandleTag) -\> PM Q)
> -\> RWST
> (Maybe GroupIndex)
> \[Either Tag GroupInfo\]
> (\[OP\] -\> \[OP\], Tag)
> Data.Functor.Identity.Identity
> \[Q\]
> |
> 470 | qs \<- forM (zip branches bs) (\\(branch,bTag) -\> (go branch aAdvice bTag))
> | ^^^^
> \`\`\`
> 
> \`tasty\` (\[patch\](https://github.com/UnkindPartition/tasty/pull/318)):
> 
> \`\`\`
> Test/Tasty/Patterns/Eval.hs:122:29: error:
> • Variable not in scope:
> (\<=\<)
> :: (Value -\> M Int)
> -\> (Expr -\> M Value) -\> Expr -\> ReaderT Path (Either String) Int
> • Perhaps you meant one of these:
> ‘=\<\<’ (imported from Prelude), ‘\<=’ (imported from Prelude)
> |
> 122 | mb\_n \<- traverse (asN \<=\< eval) mb\_e3
> | ^^^
> \`\`\`
> 
> \---
> 
> \*\*EDIT:\*\* More breakage
> 
> \`pattern-arrows\`:
> 
> \`\`\`
> src/Control/PatternArrows.hs:65:16: error:
> Variable not in scope:
> fix :: (Pattern u a r -\> Pattern u a r) -\> Pattern u a r
> |
> 65 | chainl g f p = fix $ \\c -\> g \>\>\> ((c \<+\> p) \*\*\* p) \>\>\> A.arr (uncurry f)
> | ^^^
> 
> src/Control/PatternArrows.hs:71:16: error:
> Variable not in scope:
> fix :: (Pattern u a r -\> Pattern u a r) -\> Pattern u a r
> |
> 71 | chainr g f p = fix $ \\c -\> g \>\>\> (p \*\*\* (c \<+\> p)) \>\>\> A.arr (uncurry f)
> | ^^^
> 
> src/Control/PatternArrows.hs:77:14: error:
> Variable not in scope:
> fix :: (Pattern u a r -\> Pattern u a r) -\> Pattern u a r
> |
> 77 | wrap g f p = fix $ \\c -\> g \>\>\> (C.id \*\*\* (c \<+\> p)) \>\>\> A.arr (uncurry f)
> | ^^^
> \`\`\`
> 
> \`aeson-better-errors\`:
> 
> \`\`\`
> src/Data/Aeson/BetterErrors/Internal.hs:431:3: error:
> • Variable not in scope:
> forM
> :: \[(a0, A.Value)\]
> -\> ((Int, A.Value) -\> ParseT err m a) -\> ParseT err m \[a\]
> • Perhaps you meant one of these:
> ‘V.forM’ (imported from Data.Vector),
> ‘V.forM\_’ (imported from Data.Vector),
> ‘V.iforM’ (imported from Data.Vector)
> Perhaps you want to add ‘forM’ to the import list in the import of
> ‘Data.Vector’ (src/Data/Aeson/BetterErrors/Internal.hs:32:1-25).
> |
> 431 | forM xs $ \\(i, x) -\>
> | ^^^^
> 
> src/Data/Aeson/BetterErrors/Internal.hs:439:3: error:
> • Variable not in scope:
> forM
> :: \[(Text, A.Value)\]
> -\> ((Text, A.Value) -\> ParseT err m a) -\> ParseT err m \[a\]
> • Perhaps you meant one of these:
> ‘V.forM’ (imported from Data.Vector),
> ‘V.forM\_’ (imported from Data.Vector),
> ‘V.iforM’ (imported from Data.Vector)
> Perhaps you want to add ‘forM’ to the import list in the import of
> ‘Data.Vector’ (src/Data/Aeson/BetterErrors/Internal.hs:32:1-25).
> |
> 439 | forM xs $ \\(k, x) -\>
> | ^^^^
> \`\`\`
> 
> \`mfsolve\`:
> 
> \`\`\`
> Math/MFSolve.hs:265:68: error:
> Not in scope: type constructor or class ‘MonadIO’
> Perhaps you meant ‘Monad’ (imported from Prelude)
> |
> 265 | deriving (Functor, Applicative, Monad, MonadIO, MonadState (Dependencies v n),
> | ^^^^^^^
> \`\`\`
> 
> \`bytes\`:
> 
> \`\`\`
> src/Data/Bytes/Get.hs:232:5: error:
> Variable not in scope: unless :: Bool -\> m14 a42 -\> B.Get a43
> |
> 232 | unless (Strict.length bs \>= n) $ Fail.fail "ensure: Required more bytes"
> | ^^^^^^
> 
> src/Data/Bytes/Get.hs:319:45: error:
> • Variable not in scope:
> liftM
> :: (Either c16 c16 -\> c16)
> -\> m12 (Either a38 b37) -\> m (Maybe a, s)
> • Perhaps you meant ‘lift’ (imported from Control.Monad.Writer.Strict)
> |
> 319 | lookAheadM (Lazy.StateT m) = Lazy.StateT (liftM factor . lookAheadE . liftM distribute . m)
> | ^^^^^
> \`\`\`
> 
> \`logict\`:
> 
> \`\`\`
> Control/Monad/Logic/Class.hs:30:8: error:
> Not in scope: type constructor or class ‘MonadPlus’
> |
> 30 | class (MonadPlus m) =\> MonadLogic m where
> | ^^^^^^^^^
> \`\`\`
> 
> \`monad-par\`:
> 
> \<details\>
> 
> \`\`\`
> Control/Monad/Par/Scheds/Direct.hs:210:3: error:
> Variable not in scope: when :: Bool -\> IO () -\> IO a1
> |
> 210 | when dbg $ case mb of
> | ^^^^
> 
> Control/Monad/Par/Scheds/Direct.hs:220:3: error:
> Variable not in scope: when :: Bool -\> IO () -\> IO a3
> |
> 220 | when dbg $ do sn \<- makeStableName task
> | ^^^^
> 
> Control/Monad/Par/Scheds/Direct.hs:234:3: error:
> Variable not in scope: when :: Bool -\> IO () -\> IO ()
> |
> 234 | when (not (Prelude.null idles)) $ do
> | ^^^^
> 
> Control/Monad/Par/Scheds/Direct.hs:235:5: error:
> Variable not in scope: when :: Bool -\> t1 -\> IO a2
> |
> 235 | when dbg$ printf "Waking %d idle thread(s).\\n" (length idles)
> | ^^^^
> 
> Control/Monad/Par/Scheds/Direct.hs:272:24: error:
> Variable not in scope: when :: Bool -\> Par () -\> Par a23
> |
> 272 | let userComp' = do when dbg$ io$ do
> | ^^^^
> 
> Control/Monad/Par/Scheds/Direct.hs:278:31: error:
> Variable not in scope: when :: Bool -\> IO () -\> IO a24
> |
> 278 | io$ do when (dbglvl\>=1) $ do
> | ^^^^
> 
> Control/Monad/Par/Scheds/Direct.hs:287:28: error:
> • Variable not in scope:
> liftIO :: IO Bool -\> RD.ReaderT Sched IO t12
> • Perhaps you meant one of these:
> ‘lift’ (imported from Control.Monad.Cont),
> ‘liftA’ (imported from Control.Applicative),
> ‘liftA2’ (imported from Control.Applicative)
> |
> 287 | loop n = do flg \<- liftIO$ readIORef newFlag
> | ^^^^^^
> 
> Control/Monad/Par/Scheds/Direct.hs:288:21: error:
> Variable not in scope:
> unless :: t12 -\> RD.ReaderT Sched IO () -\> RD.ReaderT Sched IO ()
> |
> 288 | unless flg $ do
> | ^^^^^^
> 
> Control/Monad/Par/Scheds/Direct.hs:289:23: error:
> Variable not in scope:
> when :: Bool -\> t13 -\> RD.ReaderT Sched IO a22
> |
> 289 | when dbg $ liftIO$ do
> | ^^^^
> 
> Control/Monad/Par/Scheds/Direct.hs:289:34: error:
> • Variable not in scope: liftIO :: IO () -\> t13
> • Perhaps you meant one of these:
> ‘lift’ (imported from Control.Monad.Cont),
> ‘liftA’ (imported from Control.Applicative),
> ‘liftA2’ (imported from Control.Applicative)
> |
> 289 | when dbg $ liftIO$ do
> | ^^^^^^
> 
> Control/Monad/Par/Scheds/Direct.hs:301:5: error:
> Variable not in scope: when :: Bool -\> IO () -\> IO a25
> |
> 301 | when (dbglvl\>=1)$ do
> | ^^^^
> 
> Control/Monad/Par/Scheds/Direct.hs:350:8: error:
> Variable not in scope: when :: Bool -\> t14 -\> IO a26
> |
> 350 | when (dbglvl\>=1)$ printf " \[%d %s\] runPar called from existing worker thread, new session (%d)....\\n" (no sched) (show tid) (sid0 + 1)
> | ^^^^
> 
> Control/Monad/Par/Scheds/Direct.hs:361:21: error:
> • Variable not in scope:
> forM
> :: \[(a34, Sched)\]
> -\> ((Int, Sched) -\> IO (Maybe (MVar Int))) -\> IO \[Maybe a32\]
> • Perhaps you meant one of these:
> ‘PC.fork’ (imported from Control.Monad.Par.Class),
> ‘fork’ (line 576)
> |
> 361 | doneFlags \<- forM (zip \[0..\] allscheds) $ \\(cpu,sched) -\> do
> | ^^^^
> 
> Control/Monad/Par/Scheds/Direct.hs:371:26: error:
> Variable not in scope: when :: Bool -\> t15 -\> IO a27
> |
> 371 | then do when dbg$ printf " \[%d %s\] Anonymous worker entering scheduling loop.\\n" cpu (show tid2)
> | ^^^^
> 
> Control/Monad/Par/Scheds/Direct.hs:373:26: error:
> Variable not in scope: when :: Bool -\> t16 -\> IO a28
> |
> 373 | when dbg$ printf " \[%d\] Anonymous worker exited scheduling loop. FINISHED.\\n" cpu
> | ^^^^
> 
> Control/Monad/Par/Scheds/Direct.hs:379:26: error:
> Variable not in scope: when :: Bool -\> t17 -\> IO a29
> |
> 379 | when dbg$ do printf " \*\*\* Out of entire runContT user computation on main thread %s.\\n" (show tid2)
> | ^^^^
> 
> Control/Monad/Par/Scheds/Direct.hs:387:8: error:
> Variable not in scope: when :: Bool -\> m3 b4 -\> IO a30
> |
> 387 | when \_WAIT\_FOR\_WORKERS $ do
> | ^^^^
> 
> Control/Monad/Par/Scheds/Direct.hs:388:12: error:
> Variable not in scope: when :: Bool -\> t18 -\> m3 a31
> |
> 388 | when dbg$ printf " \*\*\* \[%s\] Originator thread: waiting for workers to complete." (show tidorig)
> | ^^^^
> 
> Control/Monad/Par/Scheds/Direct.hs:389:12: error:
> Variable not in scope:
> forM\_ :: \[a32\] -\> (MVar a35 -\> IO b5) -\> m3 b4
> |
> 389 | forM\_ (catMaybes doneFlags) $ \\ mv -\> do
> | ^^^^^
> 
> Control/Monad/Par/Scheds/Direct.hs:392:14: error:
> Variable not in scope: when :: Bool -\> t19 -\> IO b5
> |
> 392 | when dbg$ printf " \* \[%s\] Worker %s completed\\n" (show tidorig) (show n)
> | ^^^^
> 
> Control/Monad/Par/Scheds/Direct.hs:394:8: error:
> Variable not in scope: when :: Bool -\> t20 -\> IO a33
> |
> 394 | when dbg$ do printf " \*\*\* \[%s\] Reading final MVar on originator thread.\\n" (show tidorig)
> | ^^^^
> 
> Control/Monad/Par/Scheds/Direct.hs:411:4: error:
> Variable not in scope: when :: Bool -\> IO () -\> IO a4
> |
> 411 | when dbg$ do tid \<- myThreadId
> | ^^^^
> 
> Control/Monad/Par/Scheds/Direct.hs:413:17: error:
> • Variable not in scope:
> replicateM
> :: Int -\> IO (SimpleDeque elt0) -\> IO \[SimpleDeque (Par ())\]
> • Perhaps you meant ‘replicate’ (imported from Prelude)
> |
> 413 | workpools \<- replicateM numCapabilities $ R.newQ
> | ^^^^^^^^^^
> 
> Control/Monad/Par/Scheds/Direct.hs:414:17: error:
> • Variable not in scope:
> replicateM
> :: Int
> -\> IO (HotVar (Random.Gen ghc-prim-0.6.1:GHC.Prim.RealWorld))
> -\> IO \[HotVar (Random.Gen ghc-prim-0.6.1:GHC.Prim.RealWorld)\]
> • Perhaps you meant ‘replicate’ (imported from Prelude)
> |
> 414 | rngs \<- replicateM numCapabilities $ Random.create \>\>= newHotVar
> | ^^^^^^^^^^
> 
> Control/Monad/Par/Scheds/Direct.hs:592:7: error:
> Variable not in scope: when :: Bool -\> Par () -\> Par ()
> |
> 592 | when dbg$ do
> | ^^^^
> 
> Control/Monad/Par/Scheds/Direct.hs:599:7: error:
> Variable not in scope: when :: Bool -\> Par () -\> Par a13
> |
> 599 | when dbg$ io$ printf " \[%d\] forking task...\\n" (no sch)
> | ^^^^
> 
> Control/Monad/Par/Scheds/Direct.hs:612:3: error:
> Variable not in scope:
> when :: Bool -\> t6 -\> RD.ReaderT Sched IO a14
> |
> 612 | when dbg$ liftIO$ do tid \<- myThreadId
> | ^^^^
> 
> Control/Monad/Par/Scheds/Direct.hs:612:13: error:
> • Variable not in scope: liftIO :: IO () -\> t6
> • Perhaps you meant one of these:
> ‘lift’ (imported from Control.Monad.Cont),
> ‘liftA’ (imported from Control.Applicative),
> ‘liftA2’ (imported from Control.Applicative)
> |
> 612 | when dbg$ liftIO$ do tid \<- myThreadId
> | ^^^^^^
> 
> Control/Monad/Par/Scheds/Direct.hs:617:13: error:
> • Variable not in scope:
> liftIO
> :: IO (Maybe (Par ())) -\> RD.ReaderT Sched IO (Maybe (Par a19))
> • Perhaps you meant one of these:
> ‘lift’ (imported from Control.Monad.Cont),
> ‘liftA’ (imported from Control.Applicative),
> ‘liftA2’ (imported from Control.Applicative)
> |
> 617 | mtask \<- liftIO$ popWork mysched
> | ^^^^^^
> 
> Control/Monad/Par/Scheds/Direct.hs:620:43: error:
> • Variable not in scope:
> liftIO :: IO \[Session\] -\> RD.ReaderT Sched IO \[Session\]
> • Perhaps you meant one of these:
> ‘lift’ (imported from Control.Monad.Cont),
> ‘liftA’ (imported from Control.Applicative),
> ‘liftA2’ (imported from Control.Applicative)
> |
> 620 | (Session \_ finRef):\_ \<- liftIO$ readIORef $ sessions mysched
> | ^^^^^^
> 
> Control/Monad/Par/Scheds/Direct.hs:621:26: error:
> • Variable not in scope:
> liftIO :: IO Bool -\> RD.ReaderT Sched IO Bool
> • Perhaps you meant one of these:
> ‘lift’ (imported from Control.Monad.Cont),
> ‘liftA’ (imported from Control.Applicative),
> ‘liftA2’ (imported from Control.Applicative)
> |
> 621 | fin \<- liftIO$ readIORef finRef
> | ^^^^^^
> 
> Control/Monad/Par/Scheds/Direct.hs:623:28: error:
> Variable not in scope:
> when :: Bool -\> t7 -\> RD.ReaderT Sched IO a15
> |
> 623 | then do when (dbglvl \>= 1) $ liftIO $ do
> | ^^^^
> 
> Control/Monad/Par/Scheds/Direct.hs:623:49: error:
> • Variable not in scope: liftIO :: IO b2 -\> t7
> • Perhaps you meant one of these:
> ‘lift’ (imported from Control.Monad.Cont),
> ‘liftA’ (imported from Control.Applicative),
> ‘liftA2’ (imported from Control.Applicative)
> |
> 623 | then do when (dbglvl \>= 1) $ liftIO $ do
> | ^^^^^^
> 
> Control/Monad/Par/Scheds/Direct.hs:629:30: error:
> Variable not in scope: when :: Bool -\> t9 -\> IO b2
> |
> 629 | when (not empt) $ do
> | ^^^^
> 
> Control/Monad/Par/Scheds/Direct.hs:640:22: error:
> • Variable not in scope: liftIO :: IO () -\> RD.ReaderT Sched IO a16
> • Perhaps you meant one of these:
> ‘lift’ (imported from Control.Monad.Cont),
> ‘liftA’ (imported from Control.Applicative),
> ‘liftA2’ (imported from Control.Applicative)
> |
> 640 | liftIO$ steal mysched
> | ^^^^^^
> 
> Control/Monad/Par/Scheds/Direct.hs:644:22: error:
> • Variable not in scope: liftIO :: IO () -\> RD.ReaderT Sched IO a17
> • Perhaps you meant one of these:
> ‘lift’ (imported from Control.Monad.Cont),
> ‘liftA’ (imported from Control.Applicative),
> ‘liftA2’ (imported from Control.Applicative)
> |
> 644 | liftIO yield
> | ^^^^^^
> 
> Control/Monad/Par/Scheds/Direct.hs:648:8: error:
> Variable not in scope:
> when :: Bool -\> m2 b3 -\> RD.ReaderT Sched IO a18
> |
> 648 | when dbg $ do sn \<- liftIO$ makeStableName task
> | ^^^^
> 
> Control/Monad/Par/Scheds/Direct.hs:648:28: error:
> • Variable not in scope:
> liftIO
> :: IO (GHC.StableName.StableName (Par a19))
> -\> m2 (GHC.StableName.StableName a20)
> • Perhaps you meant one of these:
> ‘lift’ (imported from Control.Monad.Cont),
> ‘liftA’ (imported from Control.Applicative),
> ‘liftA2’ (imported from Control.Applicative)
> |
> 648 | when dbg $ do sn \<- liftIO$ makeStableName task
> | ^^^^^^
> 
> Control/Monad/Par/Scheds/Direct.hs:649:22: error:
> • Variable not in scope: liftIO :: t10 -\> m2 b3
> • Perhaps you meant one of these:
> ‘lift’ (imported from Control.Monad.Cont),
> ‘liftA’ (imported from Control.Applicative),
> ‘liftA2’ (imported from Control.Applicative)
> |
> 649 | liftIO$ printf " \[%d\] popped work %d from own queue\\n" (no mysched) (hashStableName sn)
> | ^^^^^^
> 
> Control/Monad/Par/Scheds/Direct.hs:654:12: error:
> Variable not in scope:
> when
> :: Bool -\> t8 -\> Control.Monad.Par.Scheds.DirectInternal.ROnly a21
> |
> 654 | when dbg$ liftIO$ printf " + task finished successfully on cpu %d, calling reschedule continuation..\\n" (no sch)
> | ^^^^
> 
> Control/Monad/Par/Scheds/Direct.hs:654:22: error:
> • Variable not in scope: liftIO :: t11 -\> t8
> • Perhaps you meant one of these:
> ‘lift’ (imported from Control.Monad.Cont),
> ‘liftA’ (imported from Control.Applicative),
> ‘liftA2’ (imported from Control.Applicative)
> |
> 654 | when dbg$ liftIO$ printf " + task finished successfully on cpu %d, calling reschedule continuation..\\n" (no sch)
> | ^^^^^^
> 
> Control/Monad/Par/Scheds/Direct.hs:664:3: error:
> Variable not in scope: when :: Bool -\> IO () -\> IO a12
> |
> 664 | when (dbglvl\>=2)$ do tid \<- myThreadId
> | ^^^^
> 
> Control/Monad/Par/Scheds/Direct.hs:681:22: error:
> Variable not in scope: when :: Bool -\> t2 -\> IO a5
> |
> 681 | when dbg$ printf " \[%d\] | waking up all threads\\n" my\_no
> | ^^^^
> 
> Control/Monad/Par/Scheds/Direct.hs:690:26: error:
> Variable not in scope: when :: Bool -\> t3 -\> IO a6
> |
> 690 | when dbg$ printf " \[%d\] | shutting down\\n" my\_no
> | ^^^^
> 
> Control/Monad/Par/Scheds/Direct.hs:693:26: error:
> Variable not in scope: when :: Bool -\> t4 -\> IO a7
> |
> 693 | when dbg$ printf " \[%d\] | woken up\\n" my\_no
> | ^^^^
> 
> Control/Monad/Par/Scheds/Direct.hs:708:10: error:
> Variable not in scope: when :: Bool -\> t5 -\> IO a8
> |
> 708 | when (dbglvl\>=2)$ printf " \[%d\] | trying steal from %d\\n" my\_no (no schd)
> | ^^^^
> 
> Control/Monad/Par/Scheds/Direct.hs:716:15: error:
> Variable not in scope: when :: Bool -\> IO () -\> IO a9
> |
> 716 | when dbg$ do sn \<- makeStableName task
> | ^^^^
> 
> Control/Monad/Par/Scheds/Direct.hs:721:20: error:
> Variable not in scope:
> when
> :: Bool
> -\> m0 b1 -\> Control.Monad.Par.Scheds.DirectInternal.ROnly a10
> |
> 721 | when dbg$ do sn \<- liftIO$ makeStableName task
> | ^^^^
> 
> Control/Monad/Par/Scheds/Direct.hs:721:39: error:
> • Variable not in scope:
> liftIO
> :: IO (GHC.StableName.StableName (Par ()))
> -\> m0 (GHC.StableName.StableName a11)
> • Perhaps you meant one of these:
> ‘lift’ (imported from Control.Monad.Cont),
> ‘liftA’ (imported from Control.Applicative),
> ‘liftA2’ (imported from Control.Applicative)
> |
> 721 | when dbg$ do sn \<- liftIO$ makeStableName task
> | ^^^^^^
> 
> Control/Monad/Par/Scheds/Direct.hs:722:33: error:
> • Variable not in scope: liftIO :: t0 -\> m0 b1
> • Perhaps you meant one of these:
> ‘lift’ (imported from Control.Monad.Cont),
> ‘liftA’ (imported from Control.Applicative),
> ‘liftA2’ (imported from Control.Applicative)
> |
> 722 | liftIO$ printf " \[%d\] | DONE running stolen work (unit %d) from %d\\n" my\_no (hashStableName sn) (no schd)
> | ^^^^^^
> 
> Control/Monad/Par/Scheds/Direct.hs:863:3: error:
> Variable not in scope:
> forM\_ :: \[Sched\] -\> (Sched -\> IO b0) -\> IO a0
> |
> 863 | forM\_ allscheds $ \\ Sched{no, workpool} -\> do
> | ^^^^^
> 
> Control/Monad/Par/Scheds/Direct.hs:865:6: error:
> Variable not in scope: when :: Bool -\> m1 () -\> IO b0
> |
> 865 | when (not b) $ do
> | ^^^^
> \`\`\`
> 
> \</details\>
> 
> \*\*EDIT 2:\*\* Even more breakage
> 
> \`repline\`:
> 
> \<details\>
> 
> \`\`\`
> src/System/Console/Repline.hs:185:7: error:
> Not in scope: type constructor or class ‘MonadIO’
> Perhaps you meant ‘Monad’ (imported from Prelude)
> |
> 185 | MonadIO,
> | ^^^^^^^
> 
> src/System/Console/Repline.hs:186:7: error:
> Not in scope: type constructor or class ‘MonadFix’
> Perhaps you meant ‘MonadFail’ (imported from Control.Monad.Fail)
> |
> 186 | MonadFix,
> | ^^^^^^^^
> 
> src/System/Console/Repline.hs:195:32: error:
> Not in scope: type constructor or class ‘MonadIO’
> Perhaps you meant ‘Monad’ (imported from Prelude)
> |
> 195 | runHaskelineT :: (MonadMask m, MonadIO m) =\> H.Settings m -\> HaskelineT m a -\> m a
> | ^^^^^^^
> 
> src/System/Console/Repline.hs:204:24: error:
> Not in scope: type constructor or class ‘MonadIO’
> Perhaps you meant ‘Monad’ (imported from Prelude)
> |
> 204 | instance (MonadMask m, MonadIO m) =\> MonadHaskeline (H.InputT m) where
> | ^^^^^^^
> 
> src/System/Console/Repline.hs:258:28: error:
> Not in scope: type constructor or class ‘MonadIO’
> Perhaps you meant ‘Monad’ (imported from Prelude)
> |
> 258 | tryAction :: (MonadMask m, MonadIO m) =\> HaskelineT m a -\> HaskelineT m a
> | ^^^^^^^
> 
> src/System/Console/Repline.hs:264:15: error:
> Not in scope: type constructor or class ‘MonadIO’
> Perhaps you meant ‘Monad’ (imported from Prelude)
> |
> 264 | dontCrash :: (MonadIO m, MonadCatch m) =\> m () -\> m ()
> | ^^^^^^^
> 
> src/System/Console/Repline.hs:273:28: error:
> Not in scope: type constructor or class ‘MonadIO’
> Perhaps you meant ‘Monad’ (imported from Prelude)
> |
> 273 | (Functor m, MonadMask m, MonadIO m) =\>
> | ^^^^^^^
> 
> src/System/Console/Repline.hs:371:31: error:
> Not in scope: type constructor or class ‘MonadIO’
> Perhaps you meant ‘Monad’ (imported from Prelude)
> |
> 371 | evalReplOpts :: (MonadMask m, MonadIO m) =\> ReplOpts m -\> m ()
> | ^^^^^^^
> 
> src/System/Console/Repline.hs:385:17: error:
> Not in scope: type constructor or class ‘MonadIO’
> Perhaps you meant ‘Monad’ (imported from Prelude)
> |
> 385 | (MonadMask m, MonadIO m) =\>
> | ^^^^^^^
> 
> src/System/Console/Repline.hs:437:16: error:
> Not in scope: type constructor or class ‘MonadIO’
> Perhaps you meant ‘Monad’ (imported from Prelude)
> |
> 437 | mkCompleter :: MonadIO m =\> CompleterStyle m -\> CompletionFunc m
> | ^^^^^^^
> 
> src/System/Console/Repline.hs:476:18: error:
> Not in scope: type constructor or class ‘MonadIO’
> Perhaps you meant ‘Monad’ (imported from Prelude)
> |
> 476 | fileCompleter :: MonadIO m =\> CompletionFunc m
> | ^^^^^^^
> \`\`\`
> 
> \</details\>
> 
> \---
> 
> I wonder whether it might be better to continue to re-export a selected (stable) set of combinators and possibly also classes like \`MonadIO\` and \`MonadFix\`.
> 
> For combinators like \`liftM2\`, \`when\` or \`(\<=\<)\`, I don't see how this could do any harm by causing compatibility issues down the road.
> 
> In the case of classes like \`MonadIO\` and \`MonadFix\` I'm less sure, but even for these it might be no worse to cause the breakage once it's warranted by upstream changes on these classes themselves.
> 
> What do you think?