diff --git a/.github/workflows/haskell-ci-hackage.patch b/.github/workflows/haskell-ci-hackage.patch
index 105f75b..683f3ac 100644
--- a/.github/workflows/haskell-ci-hackage.patch
+++ b/.github/workflows/haskell-ci-hackage.patch
@@ -38,7 +38,7 @@ set in GitHub repository secrets.
    linux:
      name: Haskell-CI - Linux - ${{ matrix.compiler }}
 @@ -33,6 +40,7 @@
-             compilerVersion: 9.8.2
+             compilerVersion: 9.8.4
              setup-method: ghcup
              allow-failure: false
 +            upload: true
diff --git a/.github/workflows/haskell-ci.yml b/.github/workflows/haskell-ci.yml
index 0f4db51..1be4aa9 100644
--- a/.github/workflows/haskell-ci.yml
+++ b/.github/workflows/haskell-ci.yml
@@ -8,9 +8,9 @@
 #
 # For more information, see https://github.com/haskell-CI/haskell-ci
 #
-# version: 0.19.20240708
+# version: 0.19.20241219
 #
-# REGENDATA ("0.19.20240708",["github","cabal.project"])
+# REGENDATA ("0.19.20241219",["github","cabal.project"])
 #
 name: Haskell-CI
 on:
@@ -35,14 +35,19 @@ jobs:
     strategy:
       matrix:
         include:
+          - compiler: ghc-9.12.1
+            compilerKind: ghc
+            compilerVersion: 9.12.1
+            setup-method: ghcup
+            allow-failure: false
           - compiler: ghc-9.10.1
             compilerKind: ghc
             compilerVersion: 9.10.1
             setup-method: ghcup
             allow-failure: false
-          - compiler: ghc-9.8.2
+          - compiler: ghc-9.8.4
             compilerKind: ghc
-            compilerVersion: 9.8.2
+            compilerVersion: 9.8.4
             setup-method: ghcup
             allow-failure: false
             upload: true
@@ -98,17 +103,31 @@ jobs:
             allow-failure: false
       fail-fast: false
     steps:
-      - name: apt
+      - name: apt-get install
         run: |
           apt-get update
           apt-get install -y --no-install-recommends gnupg ca-certificates dirmngr curl git software-properties-common libtinfo5 libnuma-dev
+          apt-get install -y libx11-dev libxext-dev libxinerama-dev libxrandr-dev libxss-dev
+      - name: Install GHCup
+        run: |
           mkdir -p "$HOME/.ghcup/bin"
           curl -sL https://downloads.haskell.org/ghcup/0.1.30.0/x86_64-linux-ghcup-0.1.30.0 > "$HOME/.ghcup/bin/ghcup"
           chmod a+x "$HOME/.ghcup/bin/ghcup"
+      - name: Install cabal-install (prerelease)
+        run: |
+          "$HOME/.ghcup/bin/ghcup" config add-release-channel https://raw.githubusercontent.com/haskell/ghcup-metadata/master/ghcup-prereleases-0.0.8.yaml;
+          "$HOME/.ghcup/bin/ghcup" install cabal 3.15.0.0.2024.10.3 || (cat "$HOME"/.ghcup/logs/*.* && false)
+          echo "CABAL=$HOME/.ghcup/bin/cabal-3.15.0.0.2024.10.3 -vnormal+nowrap" >> "$GITHUB_ENV"
+      - name: Install GHC (GHCup)
+        if: matrix.setup-method == 'ghcup'
+        run: |
           "$HOME/.ghcup/bin/ghcup" install ghc "$HCVER" || (cat "$HOME"/.ghcup/logs/*.* && false)
-          "$HOME/.ghcup/bin/ghcup" install cabal 3.12.1.0 || (cat "$HOME"/.ghcup/logs/*.* && false)
-          apt-get update
-          apt-get install -y libx11-dev libxext-dev libxinerama-dev libxrandr-dev libxss-dev
+          HC=$("$HOME/.ghcup/bin/ghcup" whereis ghc "$HCVER")
+          HCPKG=$(echo "$HC" | sed 's#ghc$#ghc-pkg#')
+          HADDOCK=$(echo "$HC" | sed 's#ghc$#haddock#')
+          echo "HC=$HC" >> "$GITHUB_ENV"
+          echo "HCPKG=$HCPKG" >> "$GITHUB_ENV"
+          echo "HADDOCK=$HADDOCK" >> "$GITHUB_ENV"
         env:
           HCKIND: ${{ matrix.compilerKind }}
           HCNAME: ${{ matrix.compiler }}
@@ -119,21 +138,12 @@ jobs:
           echo "LANG=C.UTF-8" >> "$GITHUB_ENV"
           echo "CABAL_DIR=$HOME/.cabal" >> "$GITHUB_ENV"
           echo "CABAL_CONFIG=$HOME/.cabal/config" >> "$GITHUB_ENV"
-          HCDIR=/opt/$HCKIND/$HCVER
-          HC=$("$HOME/.ghcup/bin/ghcup" whereis ghc "$HCVER")
-          HCPKG=$(echo "$HC" | sed 's#ghc$#ghc-pkg#')
-          HADDOCK=$(echo "$HC" | sed 's#ghc$#haddock#')
-          echo "HC=$HC" >> "$GITHUB_ENV"
-          echo "HCPKG=$HCPKG" >> "$GITHUB_ENV"
-          echo "HADDOCK=$HADDOCK" >> "$GITHUB_ENV"
-          echo "CABAL=$HOME/.ghcup/bin/cabal-3.12.1.0 -vnormal+nowrap" >> "$GITHUB_ENV"
           HCNUMVER=$(${HC} --numeric-version|perl -ne '/^(\d+)\.(\d+)\.(\d+)(\.(\d+))?$/; print(10000 * $1 + 100 * $2 + ($3 == 0 ? $5 != 1 : $3))')
           echo "HCNUMVER=$HCNUMVER" >> "$GITHUB_ENV"
           echo "ARG_TESTS=--enable-tests" >> "$GITHUB_ENV"
           echo "ARG_BENCH=--enable-benchmarks" >> "$GITHUB_ENV"
-          echo "HEADHACKAGE=false" >> "$GITHUB_ENV"
+          if [ $((HCNUMVER >= 91200)) -ne 0 ] ; then echo "HEADHACKAGE=true" >> "$GITHUB_ENV" ; else echo "HEADHACKAGE=false" >> "$GITHUB_ENV" ; fi
           echo "ARG_COMPILER=--$HCKIND --with-compiler=$HC" >> "$GITHUB_ENV"
-          echo "GHCJSARITH=0" >> "$GITHUB_ENV"
         env:
           HCKIND: ${{ matrix.compilerKind }}
           HCNAME: ${{ matrix.compiler }}
@@ -160,6 +170,18 @@ jobs:
           repository hackage.haskell.org
             url: http://hackage.haskell.org/
           EOF
+          if $HEADHACKAGE; then
+          cat >> $CABAL_CONFIG <<EOF
+          repository head.hackage.ghc.haskell.org
+             url: https://ghc.gitlab.haskell.org/head.hackage/
+             secure: True
+             root-keys: 7541f32a4ccca4f97aea3b22f5e593ba2c0267546016b992dfadcd2fe944e55d
+                        26021a13b401500c8eb2761ca95c61f2d625bfef951b939a8124ed12ecf07329
+                        f76d08be13e9a61a377a85e2fb63f4c5435d40f8feb3e12eb05905edb8cdea89
+             key-threshold: 3
+          active-repositories: hackage.haskell.org, head.hackage.ghc.haskell.org:override
+          EOF
+          fi
           cat >> $CABAL_CONFIG <<EOF
           program-default-options
             ghc-options: $GHCJOBS +RTS -M3G -RTS
@@ -216,6 +238,9 @@ jobs:
           package X11
             flags: +pedantic
           EOF
+          if $HEADHACKAGE; then
+          echo "allow-newer: $($HCPKG list --simple-output | sed -E 's/([a-zA-Z-]+)-[0-9.]+/*:\1,/g')" >> cabal.project
+          fi
           $HCPKG list --simple-output --names-only | perl -ne 'for (split /\s+/) { print "constraints: any.$_ installed\n" unless /^(X11)$/; }' >> cabal.project.local
           cat cabal.project
           cat cabal.project.local
@@ -255,8 +280,8 @@ jobs:
           rm -f cabal.project.local
           $CABAL v2-build $ARG_COMPILER --disable-tests --disable-benchmarks all
       - name: save cache
-        uses: actions/cache/save@v4
         if: always()
+        uses: actions/cache/save@v4
         with:
           key: ${{ runner.os }}-${{ matrix.compiler }}-${{ github.sha }}
           path: ~/.cabal/store