haskellari · phadej · May 12, 2026 · May 12, 2026
diff --git a/.github/workflows/haskell-ci.yml b/.github/workflows/haskell-ci.yml
@@ -8,9 +8,9 @@
 #
 # For more information, see https://github.com/haskell-CI/haskell-ci
 #
-# version: 0.19.20250708
+# version: 0.19.20260331
 #
-# REGENDATA ("0.19.20250708",["github","cabal.project"])
+# REGENDATA ("0.19.20260331",["github","cabal.project"])
 #
 name: Haskell-CI
 on:
@@ -20,6 +20,11 @@ on:
   pull_request:
     branches:
       - master
+  merge_group:
+    branches:
+      - master
+  workflow_dispatch:
+    {}
 jobs:
   linux:
     name: Haskell-CI - Linux - ${{ matrix.compiler }}
@@ -32,14 +37,19 @@ jobs:
     strategy:
       matrix:
         include:
+          - compiler: ghc-9.14.1
+            compilerKind: ghc
+            compilerVersion: 9.14.1
+            setup-method: ghcup
+            allow-failure: false
           - compiler: ghc-9.12.2
             compilerKind: ghc
             compilerVersion: 9.12.2
             setup-method: ghcup
             allow-failure: false
-          - compiler: ghc-9.10.2
+          - compiler: ghc-9.10.3
             compilerKind: ghc
-            compilerVersion: 9.10.2
+            compilerVersion: 9.10.3
             setup-method: ghcup
             allow-failure: false
           - compiler: ghc-9.8.4
@@ -95,8 +105,8 @@ jobs:
           chmod a+x "$HOME/.ghcup/bin/ghcup"
       - name: Install cabal-install
         run: |
-          "$HOME/.ghcup/bin/ghcup" install cabal 3.14.2.0 || (cat "$HOME"/.ghcup/logs/*.* && false)
-          echo "CABAL=$HOME/.ghcup/bin/cabal-3.14.2.0 -vnormal+nowrap" >> "$GITHUB_ENV"
+          "$HOME/.ghcup/bin/ghcup" install cabal 3.16.0.0 || (cat "$HOME"/.ghcup/logs/*.* && false)
+          echo "CABAL=$HOME/.ghcup/bin/cabal-3.16.0.0 -vnormal+nowrap" >> "$GITHUB_ENV"
       - name: Install GHC (GHCup)
         if: matrix.setup-method == 'ghcup'
         run: |
@@ -181,7 +191,7 @@ jobs:
           chmod a+x $HOME/.cabal/bin/cabal-docspec
           cabal-docspec --version
       - name: checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v5
         with:
           path: source
       - name: initial cabal.project for sdist
@@ -209,6 +219,8 @@ jobs:
           echo "    ghc-options: -Werror=missing-methods -Werror=missing-fields" >> cabal.project
           if [ $((HCNUMVER >= 90400)) -ne 0 ] ; then echo "package tree-diff" >> cabal.project ; fi
           if [ $((HCNUMVER >= 90400)) -ne 0 ] ; then echo "    ghc-options: -Werror=unused-packages" >> cabal.project ; fi
+          if [ $((HCNUMVER >= 90000)) -ne 0 ] ; then echo "package tree-diff" >> cabal.project ; fi
+          if [ $((HCNUMVER >= 90000)) -ne 0 ] ; then echo "    ghc-options: -Werror=incomplete-patterns -Werror=incomplete-uni-patterns" >> cabal.project ; fi
           cat >> cabal.project <<EOF
           EOF
           $HCPKG list --simple-output --names-only | perl -ne 'for (split /\s+/) { print "constraints: any.$_ installed\n" unless /^(tree-diff)$/; }' >> cabal.project.local

diff --git a/ChangeLog.md b/ChangeLog.md
@@ -1,3 +1,10 @@
+## 0.4
+
+- Drop `ansi-wl-pprint` dependency, use `prettyprinter` directly.
+  The naming of functions still uses `ansiWl*` naming scheme, to avoid breaking
+  too many things. Technically, these functions are still compatible with
+  `ansi-wl-pprint` versions which use `prettyprinter` underneath.
+
 ## 0.3.4
 
 - Remove 'Eq a' requirement from 'ediffGolden'. The constraint wasn't used, as we only compare 'Expr' representations.

diff --git a/src/Data/TreeDiff/Golden.hs b/src/Data/TreeDiff/Golden.hs
@@ -10,10 +10,12 @@ import System.Console.ANSI (SGR (Reset), setSGRCode)
 import Text.Parsec         (eof, parse)
 import Text.Parsec.Text ()
 
-import qualified Data.ByteString              as BS
-import qualified Data.Text                    as T
-import qualified Data.Text.Encoding           as TE
-import qualified Text.PrettyPrint.ANSI.Leijen as WL
+import qualified Data.ByteString               as BS
+import qualified Data.Text                     as T
+import qualified Data.Text.Encoding            as TE
+import qualified Data.Text.Lazy                as TL
+import qualified Prettyprinter                 as PP
+import qualified Prettyprinter.Render.Terminal as PP.A
 
 -- | Make a golden tests.
 --
@@ -74,7 +76,9 @@ ediffGolden1 impl testName fp x = impl testName expect actual cmp wrt
         | a == b    = return Nothing
         | otherwise = return $ Just $
             setSGRCode [Reset] ++ showWL (ansiWlEditExprCompact $ ediff a b)
-    wrt expr = BS.writeFile fp $ TE.encodeUtf8 $ T.pack $ showWL (WL.plain (ansiWlExpr expr)) ++ "\n"
+    wrt expr = BS.writeFile fp $ TE.encodeUtf8 $ T.pack $ showWL (PP.unAnnotate (ansiWlExpr expr)) ++ "\n"
 
-showWL :: WL.Doc -> String
-showWL doc = WL.displayS (WL.renderSmart 0.4 80 doc) ""
+showWL :: PP.Doc PP.A.AnsiStyle -> String
+showWL doc
+    = TL.unpack $ PP.A.renderLazy
+    $ PP.layoutSmart PP.LayoutOptions { PP.layoutPageWidth = PP.AvailablePerLine 80 0.4  } doc
diff --git a/src/Data/TreeDiff/Pretty.hs b/src/Data/TreeDiff/Pretty.hs
@@ -10,7 +10,7 @@ module Data.TreeDiff.Pretty (
     prettyExpr,
     prettyEditExpr,
     prettyEditExprCompact,
-    -- * ansi-wl-pprint
+    -- * prettyprinter
     ansiWlPretty,
     ansiWlExpr,
     ansiWlEditExpr,
@@ -30,9 +30,10 @@ import Data.TreeDiff.Expr
 import Numeric            (showHex)
 import Text.Read          (readMaybe)
 
-import qualified Data.TreeDiff.OMap           as OMap
-import qualified Text.PrettyPrint             as HJ
-import qualified Text.PrettyPrint.ANSI.Leijen as WL
+import qualified Data.TreeDiff.OMap            as OMap
+import qualified Prettyprinter                 as PP
+import qualified Prettyprinter.Render.Terminal as PP.A
+import qualified Text.PrettyPrint              as HJ
 
 -- $setup
 -- >>> import qualified Data.TreeDiff.OMap as OMap
@@ -215,56 +216,73 @@ prettyEditExprCompact = ppEditExprCompact prettyPretty
 -- ansi-wl-pprint
 -------------------------------------------------------------------------------
 
--- | 'Pretty' via @ansi-wl-pprint@ library (with colors).
-ansiWlPretty :: Pretty WL.Doc
+-- | 'Pretty' via @prettyprinter@ library (with colors).
+ansiWlPretty :: Pretty (PP.Doc PP.A.AnsiStyle)
 ansiWlPretty = Pretty
-    { ppCon    = WL.text
-    , ppRec    = \c xs -> ansiGroup (c WL.<+> WL.lbrace) WL.rbrace
-               $ map (\(fn, d) -> WL.text fn WL.<+> WL.equals WL.</> d) xs
-    , ppLst    = ansiGroup WL.lbracket WL.rbracket
-    , ppCpy    = WL.dullwhite
-    , ppIns    = \d -> WL.green $ WL.plain $ WL.char '+' WL.<> d
-    , ppDel    = \d -> WL.red   $ WL.plain $ WL.char '-' WL.<> d
-    , ppApp    = \f xs -> WL.group $ WL.nest 2 $ f WL.<$> WL.vsep xs
-    , ppEdits  = WL.sep
-    , ppEllip  = WL.text "..."
-    , ppParens = WL.parens
+    { ppCon    = ppText
+    , ppRec    = \c xs -> ansiGroup (c PP.<+> PP.lbrace) PP.rbrace
+               $ map (\(fn, d) -> ppText fn PP.<+> (PP.equals PP.<> PP.softline PP.<> d)) xs
+    , ppLst    = ansiGroup PP.lbracket PP.rbracket
+    , ppCpy    = ppDullWhite
+    , ppIns    = \d -> ppGreen $ PP.unAnnotate $ ppChar '+' PP.<> d
+    , ppDel    = \d -> ppRed   $ PP.unAnnotate $ ppChar '-' PP.<> d
+    , ppApp    = \f xs -> PP.group $ PP.nest 2 $ f PP.<> PP.line PP.<> PP.vsep xs
+    , ppEdits  = PP.sep
+    , ppEllip  = ppText "..."
+    , ppParens = PP.parens
     }
 
-ansiGroup :: WL.Doc -> WL.Doc -> [WL.Doc] -> WL.Doc
-ansiGroup l r xs = WL.group $ WL.nest 2 (l WL.<$$> WL.vsep (WL.punctuate WL.comma xs) WL.<> r)
+ansiGroup :: PP.Doc PP.A.AnsiStyle -> PP.Doc PP.A.AnsiStyle -> [PP.Doc PP.A.AnsiStyle] -> PP.Doc PP.A.AnsiStyle
+ansiGroup l r xs = PP.group $ PP.nest 2 (l PP.<> ppLinebreak PP.<> PP.vsep (PP.punctuate PP.comma xs) PP.<> r)
 
 -- | Pretty print 'Expr' using @ansi-wl-pprint@.
-ansiWlExpr :: Expr -> WL.Doc
+ansiWlExpr :: Expr -> PP.Doc PP.A.AnsiStyle
 ansiWlExpr = ppExpr ansiWlPretty
 
 -- | Pretty print @'Edit' 'EditExpr'@ using @ansi-wl-pprint@.
-ansiWlEditExpr :: Edit EditExpr -> WL.Doc
+ansiWlEditExpr :: Edit EditExpr -> PP.Doc PP.A.AnsiStyle
 ansiWlEditExpr = ppEditExpr ansiWlPretty
 
 -- | Compact 'ansiWlEditExpr'
-ansiWlEditExprCompact :: Edit EditExpr -> WL.Doc
+ansiWlEditExprCompact :: Edit EditExpr -> PP.Doc PP.A.AnsiStyle
 ansiWlEditExprCompact = ppEditExprCompact ansiWlPretty
 
+ppChar :: Char -> PP.Doc PP.A.AnsiStyle
+ppChar = PP.pretty
+
+ppText :: String -> PP.Doc PP.A.AnsiStyle
+ppText = PP.pretty
+
+ppLinebreak :: PP.Doc a
+ppLinebreak = PP.flatAlt PP.line mempty
+
+ppWhite, ppDullWhite, ppRed, ppGreen, ppOnDullRed, ppOnDullGreen :: PP.Doc PP.A.AnsiStyle -> PP.Doc PP.A.AnsiStyle
+ppWhite         = PP.annotate (PP.A.color       PP.A.White)
+ppDullWhite     = PP.annotate (PP.A.colorDull   PP.A.White)
+ppRed           = PP.annotate (PP.A.color       PP.A.Red)
+ppGreen         = PP.annotate (PP.A.color       PP.A.Green)
+ppOnDullRed     = PP.annotate (PP.A.bgColorDull PP.A.Red)
+ppOnDullGreen   = PP.annotate (PP.A.bgColorDull PP.A.Green)
+
 -------------------------------------------------------------------------------
 -- Background
 -------------------------------------------------------------------------------
 
 -- | Like 'ansiWlPretty' but color the background.
-ansiWlBgPretty :: Pretty WL.Doc
+ansiWlBgPretty :: Pretty (PP.Doc PP.A.AnsiStyle)
 ansiWlBgPretty = ansiWlPretty
-    { ppIns    = \d -> WL.ondullgreen $ WL.white $ WL.plain $ WL.char '+' WL.<> d
-    , ppDel    = \d -> WL.ondullred   $ WL.white $ WL.plain $ WL.char '-' WL.<> d
+    { ppIns    = \d -> ppOnDullGreen $ ppWhite $ PP.unAnnotate $ ppChar '+' PP.<> d
+    , ppDel    = \d -> ppOnDullRed   $ ppWhite $ PP.unAnnotate $ ppChar '-' PP.<> d
     }
 
 -- | Pretty print 'Expr' using @ansi-wl-pprint@.
-ansiWlBgExpr :: Expr -> WL.Doc
+ansiWlBgExpr :: Expr -> PP.Doc PP.A.AnsiStyle
 ansiWlBgExpr = ppExpr ansiWlBgPretty
 
 -- | Pretty print @'Edit' 'EditExpr'@ using @ansi-wl-pprint@.
-ansiWlBgEditExpr :: Edit EditExpr -> WL.Doc
+ansiWlBgEditExpr :: Edit EditExpr -> PP.Doc PP.A.AnsiStyle
 ansiWlBgEditExpr = ppEditExpr ansiWlBgPretty
 
 -- | Compact 'ansiWlBgEditExpr'.
-ansiWlBgEditExprCompact :: Edit EditExpr -> WL.Doc
+ansiWlBgEditExprCompact :: Edit EditExpr -> PP.Doc PP.A.AnsiStyle
 ansiWlBgEditExprCompact = ppEditExprCompact ansiWlBgPretty
diff --git a/src/Data/TreeDiff/QuickCheck.hs b/src/Data/TreeDiff/QuickCheck.hs
@@ -7,8 +7,15 @@ import Data.TreeDiff
 import System.Console.ANSI (SGR (Reset), setSGRCode)
 import Test.QuickCheck     (Property, counterexample)
 
+import qualified Data.Text.Lazy                as TL
+import qualified Prettyprinter                 as PP
+import qualified Prettyprinter.Render.Terminal as PP.A
+
 -- | A variant of '===', which outputs a diff when values are inequal.
 ediffEq :: (Eq a, ToExpr a) => a -> a -> Property
 ediffEq x y = counterexample
-    (setSGRCode [Reset] ++ show (ansiWlEditExpr $ ediff x y))
+    (setSGRCode [Reset] ++ render (ansiWlEditExpr $ ediff x y))
     (x == y)
+
+render :: PP.Doc PP.A.AnsiStyle -> String
+render = TL.unpack . PP.A.renderLazy . PP.layoutPretty PP.defaultLayoutOptions
diff --git a/tests/Tests.hs b/tests/Tests.hs
@@ -10,12 +10,12 @@ import Test.Tasty                 (TestTree, defaultMain, testGroup)
 import Test.Tasty.Golden.Advanced (goldenTest)
 import Test.Tasty.QuickCheck      (testProperty)
 
-import qualified Data.HashSet                 as HS
-import qualified Data.Primitive               as Prim
-import qualified Text.Parsec                  as P
-import qualified Text.PrettyPrint.ANSI.Leijen as WL
-import qualified Text.Trifecta                as T (eof, parseString)
-import qualified Text.Trifecta.Result         as T (ErrInfo (..), Result (..))
+import qualified Data.HashSet         as HS
+import qualified Data.Primitive       as Prim
+import qualified Prettyprinter        as PP
+import qualified Text.Parsec          as P
+import qualified Text.Trifecta        as T (eof, parseString)
+import qualified Text.Trifecta.Result as T (ErrInfo (..), Result (..))
 
 import Data.TreeDiff
 import Data.TreeDiff.Golden
@@ -73,7 +73,7 @@ roundtripTrifectaPretty e = counterexample info $ ediffEq (Just e) res'
 roundtripParsecAnsiWl :: Expr -> Property
 roundtripParsecAnsiWl e = counterexample info $ ediffEq (Just e) res'
   where
-    doc = show (WL.plain (ansiWlExpr e))
+    doc = show (PP.unAnnotate (ansiWlExpr e))
     res = P.parse (exprParser <* P.eof) "<memory>" doc
 
     info = case res of

diff --git a/tree-diff.cabal b/tree-diff.cabal
@@ -1,6 +1,6 @@
 cabal-version:      2.2
 name:               tree-diff
-version:            0.3.5
+version:            0.4
 synopsis:           Diffing of (expression) trees.
 category:           Data, Testing
 description:
@@ -94,24 +94,25 @@ library
     , parsec      ^>=3.1.13.0
     , pretty      ^>=1.1.1.0
     , text        ^>=1.2.3.0  || ^>=2.0      || ^>=2.1
-    , time        ^>=1.8.0.2  || ^>=1.9.3    || ^>=1.10     || ^>=1.11 || ^>=1.12 || ^>=1.14 || ^>=1.16
+    , time        ^>=1.8.0.2  || ^>=1.9.3    || ^>=1.10     || ^>=1.11 || ^>=1.12 || ^>=1.14 || ^>=1.15
 
   build-depends:
-    , aeson                 ^>=2.2.0.0
-    , ansi-terminal         ^>=1.1
-    , ansi-wl-pprint        ^>=1.0.2    || ^>=1.1.1
-    , hashable              ^>=1.4.4.0  || ^>=1.5.0.0
-    , parsers               ^>=0.12.11
-    , primitive             ^>=0.9.0.0
-    , QuickCheck            ^>=2.14.2   || ^>=2.15    || ^>=2.16.0.0 || ^>=2.18.0.0
-    , scientific            ^>=0.3.8.0
-    , semialign             ^>=1.3.1    || ^>=1.4
-    , strict                ^>=0.5
-    , tagged                ^>=0.8.8
-    , these                 ^>=1.2.1
-    , unordered-containers  ^>=0.2.20
-    , uuid-types            ^>=1.0.6
-    , vector                ^>=0.13.1.0
+    , aeson                        ^>=2.2.0.0
+    , ansi-terminal                ^>=1.1
+    , hashable                     ^>=1.4.4.0  || ^>=1.5.0.0
+    , parsers                      ^>=0.12.11
+    , prettyprinter                ^>=1.7.2
+    , prettyprinter-ansi-terminal  ^>=1.1.4
+    , primitive                    ^>=0.9.0.0
+    , QuickCheck                   ^>=2.14.2   || ^>=2.15    || ^>=2.16.0.0 || ^>=2.18.0.0
+    , scientific                   ^>=0.3.8.0
+    , semialign                    ^>=1.3.1    || ^>=1.4
+    , strict                       ^>=0.5
+    , tagged                       ^>=0.8.8
+    , these                        ^>=1.2.1
+    , unordered-containers         ^>=0.2.20
+    , uuid-types                   ^>=1.0.6
+    , vector                       ^>=0.13.1.0
 
   other-extensions:
     CPP
@@ -136,9 +137,9 @@ test-suite tree-diff-test
 
   -- dependencies from library
   build-depends:
-    , ansi-wl-pprint
     , base
     , parsec
+    , prettyprinter
     , primitive
     , QuickCheck
     , tree-diff