First stab at mtl 2.3 compliance.

This will no doubt produce a bunch of warnings and hence CI
failures, which we'll need to work around with explicit imports.

.github/workflows/ci.yml

@@ -70,6 +70,11 @@ jobs:
             cabal: '3.8'
             cabalopts: ''
             testopts: '--test-option=--hide-successes --test-option=--ansi-tricks=false'
+
+          - ghc: '9.4.2'
+            cabal: '3.8'
+            cabalopts: '--allow-newer --constrain "mtl >= 2.3.1"'
+            testopts: '--test-option=--hide-successes --test-option=--ansi-tricks=false'
     steps:
     - uses: actions/checkout@v3
 

pandoc.cabal

@@ -496,7 +496,7 @@ library
                  ipynb                 >= 0.2      && < 0.3,
                  jira-wiki-markup      >= 1.4      && < 1.5,
                  mime-types            >= 0.1.1    && < 0.2,
-                 mtl                   >= 2.2      && < 2.3,
+                 mtl                   >= 2.2      && < 2.4,
                  network               >= 2.6,
                  network-uri           >= 2.6      && < 2.8,
                  pandoc-types          >= 1.22.2   && < 1.23,
@@ -750,7 +750,7 @@ test-suite test-pandoc
                   directory         >= 1.2.3   && < 1.4,
                   doctemplates      >= 0.10    && < 0.11,
                   filepath          >= 1.1     && < 1.5,
-                  mtl               >= 2.2     && < 2.3,
+                  mtl               >= 2.2     && < 2.4,
                   pandoc-types      >= 1.22.2  && < 1.23,
                   process           >= 1.2.3   && < 1.7,
                   tasty             >= 0.11    && < 1.5,
@@ -824,7 +824,7 @@ benchmark benchmark-pandoc
   hs-source-dirs:  benchmark
   build-depends:   bytestring,
                    tasty-bench >= 0.2     && <= 0.4,
-                   mtl         >= 2.2     && < 2.3,
+                   mtl         >= 2.2     && < 2.4,
                    text        >= 1.1.1.0 && < 2.1,
                    deepseq
   -- we increase heap size to avoid benchmarking garbage collection:

src/Text/Pandoc/App/Opt.hs

@@ -25,7 +25,9 @@ module Text.Pandoc.App.Opt (
           , applyDefaults
           , fullDefaultsPath
           ) where
-import Control.Monad.Except (MonadIO, liftIO, throwError, (>=>), foldM)
+import Control.Monad.Except (throwError)
+import Control.Monad.Trans (MonadIO, liftIO)
+import Control.Monad ((>=>), foldM)
 import Control.Monad.State.Strict (StateT, modify, gets)
 import System.FilePath ( addExtension, (</>), takeExtension, takeDirectory )
 import System.Directory ( canonicalizePath )

src/Text/Pandoc/Citeproc/BibTeX.hs

@@ -46,7 +46,8 @@ import qualified Data.Map               as Map
 import           Data.Maybe
 import           Text.Pandoc.Parsing hiding ((<|>), many)
 import           Control.Applicative
-import           Control.Monad.RWS      hiding ((<>))
+import           Control.Monad ( guard, MonadPlus(..), void )
+import Control.Monad.RWS ( asks, RWST, gets, modify, evalRWST )
 import qualified Data.Sequence          as Seq
 import           Data.Char              (isAlphaNum, isDigit, isLetter,
                                          isUpper, toLower, toUpper,

src/Text/Pandoc/Citeproc/Name.hs

@@ -29,7 +29,6 @@ import Citeproc.Pandoc ()
 import Text.Pandoc.Citeproc.Util (splitStrWhen)
 import qualified Data.Text              as T
 import           Data.List.Split        (splitWhen, wordsBy)
-import           Control.Monad.RWS      hiding ((<>))
 import Data.Char (isUpper, isDigit)
 import Data.List (foldl')
 
@@ -59,7 +58,7 @@ data NameOpts =
 
 -- | Parse a list of 'Inline's into a citeproc 'Name', identifying
 -- first and last name, particles, suffixes.
-toName :: MonadPlus m => NameOpts -> [Inline] -> m Name
+toName :: Monad m => NameOpts -> [Inline] -> m Name
 toName _ [Str "others"] =
   return emptyName{ nameLiteral = Just "others" }
 toName _ [Span ("",[],[]) ils] = -- corporate author

src/Text/Pandoc/Class/PandocMonad.hs

@@ -54,8 +54,9 @@ module Text.Pandoc.Class.PandocMonad
   , checkUserDataDir
   ) where
 
-import Control.Monad.Except (MonadError (catchError, throwError),
-                             MonadTrans, lift, when)
+import Control.Monad.Except (MonadError (catchError, throwError))
+import Control.Monad.Trans (MonadTrans, lift)
+import Control.Monad (when)
 import Data.Time (UTCTime)
 import Data.Time.Clock.POSIX (POSIXTime, utcTimeToPOSIXSeconds,
                              posixSecondsToUTCTime)

src/Text/Pandoc/Class/PandocPure.hs

@@ -31,6 +31,7 @@ module Text.Pandoc.Class.PandocPure
 import Codec.Archive.Zip
 import Control.Monad.Except
 import Control.Monad.State.Strict
+import Control.Monad (foldM)
 import Data.Default
 import Data.Text (Text)
 import Data.Time (UTCTime)

src/Text/Pandoc/Parsing/General.hs

@@ -67,9 +67,10 @@ import Control.Monad
   , unless
   , void
   , when
+  , MonadPlus(mzero)
   )
 import Control.Monad.Except ( MonadError(throwError) )
-import Control.Monad.Identity ( Identity(..), MonadPlus(mzero) )
+import Control.Monad.Identity ( Identity(..) )
 import Data.Char
   ( chr
   , isAlphaNum

src/Text/Pandoc/Readers/CommonMark.hs

@@ -26,6 +26,7 @@ import Text.Pandoc.Definition
 import Text.Pandoc.Builder as B
 import Text.Pandoc.Options
 import Text.Pandoc.Readers.Metadata (yamlMetaBlock)
+import Control.Monad (MonadPlus(mzero))
 import Control.Monad.Except
 import Data.Functor.Identity (runIdentity)
 import Data.Typeable

src/Text/Pandoc/Readers/Creole.hs

@@ -13,7 +13,8 @@ Conversion of creole text to 'Pandoc' document.
 module Text.Pandoc.Readers.Creole ( readCreole
                                   ) where
 
-import Control.Monad.Except (guard, liftM2, throwError)
+import Control.Monad
+import Control.Monad.Except (throwError)
 import qualified Data.Foldable as F
 import Data.Maybe (fromMaybe)
 import Data.Text (Text)

src/Text/Pandoc/Readers/DocBook.hs

@@ -13,7 +13,13 @@
 Conversion of DocBook XML to 'Pandoc' document.
 -}
 module Text.Pandoc.Readers.DocBook ( readDocBook ) where
+import Control.Monad (MonadPlus(mplus))
 import Control.Monad.State.Strict
+    ( MonadTrans(lift),
+      StateT(runStateT),
+      MonadState(get),
+      gets,
+      modify )
 import Data.ByteString (ByteString)
 import Data.FileEmbed
 import Data.Char (isSpace, isLetter, chr)

src/Text/Pandoc/Readers/Docx.hs

@@ -59,6 +59,7 @@ module Text.Pandoc.Readers.Docx
        ) where
 
 import Codec.Archive.Zip
+import Control.Monad ( liftM, unless )
 import Control.Monad.Reader
 import Control.Monad.State.Strict
 import Data.Bifunctor (bimap, first)

src/Text/Pandoc/Readers/Docx/Parse.hs

@@ -60,6 +60,7 @@ module Text.Pandoc.Readers.Docx.Parse ( Docx(..)
 import Text.Pandoc.Readers.Docx.Parse.Styles
 import Codec.Archive.Zip
 import Control.Applicative ((<|>))
+import Control.Monad
 import Control.Monad.Except
 import Control.Monad.Reader
 import Control.Monad.State.Strict

src/Text/Pandoc/Readers/JATS.hs

@@ -14,7 +14,8 @@ Conversion of JATS XML to 'Pandoc' document.
 -}
 
 module Text.Pandoc.Readers.JATS ( readJATS ) where
-import Control.Monad.State.Strict
+import Control.Monad.State.Strict ( StateT(runStateT), gets, modify )
+import Control.Monad (forM_,  when, unless, MonadPlus(mplus))
 import Control.Monad.Except (throwError)
 import Text.Pandoc.Error (PandocError(..))
 import Data.Char (isDigit, isSpace)

src/Text/Pandoc/Writers/AnnotatedTable.hs

@@ -42,7 +42,6 @@ module Text.Pandoc.Writers.AnnotatedTable
 where
 
 import           Control.Monad.RWS.Strict
-                                         hiding ( (<>) )
 import           Data.Generics                  ( Data
                                                 , Typeable
                                                 )

src/Text/Pandoc/Writers/AsciiDoc.hs

@@ -19,6 +19,7 @@ that it has omitted the construct.
 AsciiDoc:  <http://www.methods.co.nz/asciidoc/>
 -}
 module Text.Pandoc.Writers.AsciiDoc (writeAsciiDoc, writeAsciiDoctor) where
+import Control.Monad (foldM)
 import Control.Monad.State.Strict
 import Data.Char (isPunctuation, isSpace)
 import Data.List (delete, intercalate, intersperse)

src/Text/Pandoc/Writers/ConTeXt.hs

@@ -14,7 +14,9 @@
 Conversion of 'Pandoc' format into ConTeXt.
 -}
 module Text.Pandoc.Writers.ConTeXt ( writeConTeXt ) where
+import Control.Monad (liftM)
 import Control.Monad.State.Strict
+    ( StateT, MonadState(put, get), gets, modify, evalStateT )
 import Data.Char (ord, isDigit)
 import Data.List (intersperse)
 import Data.List.NonEmpty (NonEmpty ((:|)))

src/Text/Pandoc/Writers/Docx.hs

@@ -19,6 +19,7 @@ Conversion of 'Pandoc' documents to docx.
 module Text.Pandoc.Writers.Docx ( writeDocx ) where
 import Codec.Archive.Zip
 import Control.Applicative ((<|>))
+import Control.Monad (MonadPlus(mplus), unless, when)
 import Control.Monad.Except (catchError, throwError)
 import Control.Monad.Reader
 import Control.Monad.State.Strict

src/Text/Pandoc/Writers/Docx/Table.hs

@@ -13,7 +13,8 @@ module Text.Pandoc.Writers.Docx.Table
   ( tableToOpenXML
   ) where
 
-import Control.Monad.State.Strict ( modify, gets, unless )
+import Control.Monad.State.Strict ( modify, gets )
+import Control.Monad ( unless )
 import Data.Array ( elems, (!), assocs, indices )
 import Data.Text (Text)
 import Text.Pandoc.Definition

src/Text/Pandoc/Writers/FB2.hs

@@ -18,9 +18,9 @@ FictionBook is an XML-based e-book format. For more information see:
 -}
 module Text.Pandoc.Writers.FB2 (writeFB2)  where
 
-import Control.Monad (zipWithM)
+import Control.Monad (zipWithM, liftM)
 import Control.Monad.Except (catchError, throwError)
-import Control.Monad.State.Strict (StateT, evalStateT, get, gets, lift, liftM, modify)
+import Control.Monad.State.Strict (StateT, evalStateT, get, gets, lift, modify)
 import Data.ByteString.Base64 (encodeBase64)
 import Data.Char (isAscii, isControl, isSpace)
 import Data.Either (lefts, rights)

src/Text/Pandoc/Writers/HTML.hs

@@ -30,6 +30,9 @@ module Text.Pandoc.Writers.HTML (
   tagWithAttributes
   ) where
 import Control.Monad.State.Strict
+    ( StateT, MonadState(get), gets, modify, evalStateT )
+import Control.Monad ( liftM, when, foldM, unless )
+import Control.Monad.Trans ( MonadTrans(lift) )
 import Data.Char (ord)
 import Data.List (intercalate, intersperse, partition, delete, (\\), foldl')
 import Data.List.NonEmpty (NonEmpty((:|)))

src/Text/Pandoc/Writers/Haddock.hs

@@ -14,6 +14,7 @@ Conversion of 'Pandoc' documents to haddock markup.
 Haddock:  <http://www.haskell.org/haddock/doc/html/>
 -}
 module Text.Pandoc.Writers.Haddock (writeHaddock) where
+import Control.Monad (zipWithM)
 import Control.Monad.State.Strict
 import Data.Char (isAlphaNum)
 import Data.Default

src/Text/Pandoc/Writers/ICML.hs

@@ -17,6 +17,7 @@ into InDesign with File -> Place.
 -}
 module Text.Pandoc.Writers.ICML (writeICML) where
 import Control.Monad.Except (catchError)
+import Control.Monad (liftM2)
 import Control.Monad.State.Strict
 import Data.List (intersperse)
 import Data.Maybe (fromMaybe, maybeToList)

src/Text/Pandoc/Writers/Ipynb.hs

@@ -14,6 +14,7 @@ Ipynb (Jupyter notebook JSON format) writer for pandoc.
 -}
 module Text.Pandoc.Writers.Ipynb ( writeIpynb )
 where
+import Control.Monad (foldM)
 import Control.Monad.State
 import qualified Data.Map as M
 import Data.Maybe (catMaybes, fromMaybe)

src/Text/Pandoc/Writers/JATS.hs

@@ -22,6 +22,7 @@ module Text.Pandoc.Writers.JATS
   , writeJatsArticleAuthoring
   ) where
 import Control.Applicative ((<|>))
+import Control.Monad
 import Control.Monad.Reader
 import Control.Monad.State
 import Data.Generics (everywhere, mkT)

src/Text/Pandoc/Writers/LaTeX.hs

@@ -20,6 +20,15 @@ module Text.Pandoc.Writers.LaTeX (
   , writeBeamer
   ) where
 import Control.Monad.State.Strict
+    ( MonadState(get, put),
+      gets,
+      modify,
+      evalStateT )
+import Control.Monad
+    ( MonadPlus(mplus),
+      liftM,
+      when,
+      unless )
 import Data.Containers.ListUtils (nubOrd)
 import Data.Char (isDigit)
 import Data.List (intersperse, (\\))

src/Text/Pandoc/Writers/LaTeX/Table.hs

@@ -15,6 +15,7 @@ module Text.Pandoc.Writers.LaTeX.Table
   ( tableToLaTeX
   ) where
 import Control.Monad.State.Strict
+import Control.Monad (when)
 import Data.List (intersperse)
 import qualified Data.List.NonEmpty as NonEmpty
 import Data.List.NonEmpty (NonEmpty ((:|)))

src/Text/Pandoc/Writers/Man.hs

@@ -14,7 +14,9 @@ Conversion of 'Pandoc' documents to roff man page format.
 
 -}
 module Text.Pandoc.Writers.Man ( writeMan ) where
-import Control.Monad.State.Strict
+import Control.Monad ( liftM, zipWithM, forM )
+import Control.Monad.State.Strict ( StateT, gets, modify, evalStateT )
+import Control.Monad.Trans (MonadTrans(lift))
 import Data.List (intersperse)
 import Data.List.NonEmpty (nonEmpty)
 import Data.Maybe (fromMaybe)

src/Text/Pandoc/Writers/Markdown.hs

@@ -21,6 +21,7 @@ module Text.Pandoc.Writers.Markdown (
   writeCommonMark,
   writeMarkua,
   writePlain) where
+import Control.Monad (foldM, zipWithM, MonadPlus(..), when)
 import Control.Monad.Reader
 import Control.Monad.State.Strict
 import Data.Default

src/Text/Pandoc/Writers/Markdown/Inline.hs

@@ -16,6 +16,7 @@ module Text.Pandoc.Writers.Markdown.Inline (
   attrsToMarkdown,
   attrsToMarkua
   ) where
+import Control.Monad (when, liftM2)
 import Control.Monad.Reader
 import Control.Monad.State.Strict
 import Data.Char (isAlphaNum, isDigit)

src/Text/Pandoc/Writers/Ms.hs

@@ -21,6 +21,8 @@ TODO:
 
 module Text.Pandoc.Writers.Ms ( writeMs ) where
 import Control.Monad.State.Strict
+    ( gets, modify, evalStateT )
+import Control.Monad ( MonadPlus(mplus), liftM, unless, forM )
 import Data.Containers.ListUtils (nubOrd)
 import Data.Char (isAscii, isLower, isUpper, ord)
 import Data.List (intercalate, intersperse)

src/Text/Pandoc/Writers/Muse.hs

@@ -25,6 +25,7 @@ However, @\<literal style="html">@ tag is used for HTML raw blocks
 even though it is supported only in Emacs Muse.
 -}
 module Text.Pandoc.Writers.Muse (writeMuse) where
+import Control.Monad (zipWithM)
 import Control.Monad.Except (throwError)
 import Control.Monad.Reader
 import Control.Monad.State.Strict

src/Text/Pandoc/Writers/ODT.hs

@@ -13,6 +13,7 @@ Conversion of 'Pandoc' documents to ODT.
 -}
 module Text.Pandoc.Writers.ODT ( writeODT ) where
 import Codec.Archive.Zip
+import Control.Monad
 import Control.Monad.Except (catchError, throwError)
 import Control.Monad.State.Strict
 import qualified Data.ByteString.Lazy as B

src/Text/Pandoc/Writers/OOXML.hs

@@ -24,7 +24,7 @@ module Text.Pandoc.Writers.OOXML ( mknode
                                  ) where
 
 import Codec.Archive.Zip
-import Control.Monad.Reader
+import Control.Monad (mplus)
 import Control.Monad.Except (throwError)
 import Text.Pandoc.Error
 import qualified Data.ByteString as B

src/Text/Pandoc/Writers/OpenDocument.hs

@@ -15,7 +15,8 @@ Conversion of 'Pandoc' documents to OpenDocument XML.
 -}
 module Text.Pandoc.Writers.OpenDocument ( writeOpenDocument ) where
 import Control.Arrow ((***), (>>>))
-import Control.Monad.State.Strict hiding (when)
+import Control.Monad hiding (when)
+import Control.Monad.State.Strict
 import Data.Char (chr)
 import Data.Foldable (find)
 import Data.List (sortOn, sortBy, foldl')

src/Text/Pandoc/Writers/Org.hs

@@ -16,6 +16,7 @@ Conversion of 'Pandoc' documents to Emacs Org-Mode.
 Org-Mode:  <http://orgmode.org>
 -}
 module Text.Pandoc.Writers.Org (writeOrg) where
+import Control.Monad (zipWithM)
 import Control.Monad.State.Strict
 import Data.Char (isAlphaNum, isDigit)
 import Data.List (intersperse, partition, transpose)

src/Text/Pandoc/Writers/Powerpoint/Output.hs

@@ -21,6 +21,7 @@ Text.Pandoc.Writers.Powerpoint.Presentation) to a zip archive.
 module Text.Pandoc.Writers.Powerpoint.Output ( presentationToArchive
                                              ) where
 
+import Control.Monad ( MonadPlus(mplus), foldM, unless )
 import Control.Monad.Except (throwError, catchError)
 import Control.Monad.Reader
 import Control.Monad.State

src/Text/Pandoc/Writers/Powerpoint/Presentation.hs

@@ -43,7 +43,7 @@ module Text.Pandoc.Writers.Powerpoint.Presentation ( documentToPresentation
                                                    , LinkTarget(..)
                                                    ) where
 
-
+import Control.Monad
 import Control.Monad.Reader
 import Control.Monad.State
 import Data.List (intercalate)

src/Text/Pandoc/Writers/RST.hs

@@ -14,7 +14,8 @@ Conversion of 'Pandoc' documents to reStructuredText.
 reStructuredText:  <http://docutils.sourceforge.net/rst.html>
 -}
 module Text.Pandoc.Writers.RST ( writeRST, flatten ) where
-import Control.Monad.State.Strict
+import Control.Monad.State.Strict ( StateT, gets, modify, evalStateT )
+import Control.Monad (zipWithM, liftM)
 import Data.Char (isSpace, generalCategory, isAscii, isAlphaNum,
                   GeneralCategory(
                         ClosePunctuation, OpenPunctuation, InitialQuote,

src/Text/Pandoc/Writers/Texinfo.hs

@@ -12,6 +12,7 @@
 Conversion of 'Pandoc' format into Texinfo.
 -}
 module Text.Pandoc.Writers.Texinfo ( writeTexinfo ) where
+import Control.Monad (zipWithM)
 import Control.Monad.Except (throwError)
 import Control.Monad.State.Strict
 import Data.Char (chr, ord, isAlphaNum)

src/Text/Pandoc/Writers/Textile.hs

@@ -13,7 +13,8 @@ Conversion of 'Pandoc' documents to Textile markup.
 Textile:  <http://thresholdstate.com/articles/4312/the-textile-reference-manual>
 -}
 module Text.Pandoc.Writers.Textile ( writeTextile ) where
-import Control.Monad.State.Strict
+import Control.Monad (zipWithM, liftM)
+import Control.Monad.State.Strict ( StateT, gets, modify, evalStateT )
 import Data.Char (isSpace)
 import Data.Text (Text)
 import qualified Data.Text as T