From 8efac05f1e02e703e5daacdb9708ca582467f9cd Mon Sep 17 00:00:00 2001
From: Steven Shuck <stevenjshuck@gmail.com>
Date: Sun, 7 Jun 2026 11:37:25 -0400
Subject: [PATCH 1/4] Git ignore stack.yaml and stack.yaml.lock

---
 .gitignore | 1 +
 1 file changed, 1 insertion(+)

diff --git a/.gitignore b/.gitignore
index 55a715d..2ef1005 100644
--- a/.gitignore
+++ b/.gitignore
@@ -20,6 +20,7 @@ cabal.sandbox.config
 *.hp
 *.eventlog
 .stack-work/
+stack.yaml*
 cabal.project.local*
 .HTF/
 .ghc.environment.*

From e8d5c1c002b8ec18cda1cb969c601c09dff9182d Mon Sep 17 00:00:00 2001
From: Steven Shuck <stevenjshuck@gmail.com>
Date: Sun, 7 Jun 2026 11:51:54 -0400
Subject: [PATCH 2/4] Bump MHS to 0.16.0.0

---
 .github/workflows/ci.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 5ca46c8..0988e53 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -171,7 +171,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        mhs: ["0.15.4.0"]
+        mhs: ["0.16.0.0"]
       fail-fast: false
     steps:
       - name: checkout mhs repo

From 200f6c3b04a5bbf32e5567d43cee618e1bbc4ea8 Mon Sep 17 00:00:00 2001
From: Steven Shuck <stevenjshuck@gmail.com>
Date: Sun, 7 Jun 2026 13:14:42 -0400
Subject: [PATCH 3/4] Git ignore dist-mcabal (MHS)

---
 .gitignore | 1 +
 1 file changed, 1 insertion(+)

diff --git a/.gitignore b/.gitignore
index 2ef1005..bcca8b0 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,6 +1,7 @@
 dist
 dist-boot
 dist-install
+dist-mcabal
 dist-newstyle
 ghc.mk
 GNUmakefile

From 120e91dcd5f2e67cf927dcbef22f99bf03cf725e Mon Sep 17 00:00:00 2001
From: Steven Shuck <stevenjshuck@gmail.com>
Date: Mon, 8 Jun 2026 05:27:44 -0400
Subject: [PATCH 4/4] Remove CPP for ContT MonadCont instance; update
 tested-with

The kind signature does not work in MHS, and it isn't necessary in GHC,
so delete it. Test for the latter.
---
 .github/workflows/ci.yml    | 15 ++++++++++++---
 Control/Monad/Cont/Class.hs |  5 -----
 mtl.cabal                   | 11 ++++++++++-
 test/MonadCont.hs           | 19 +++++++++++++++++++
 4 files changed, 41 insertions(+), 9 deletions(-)
 create mode 100644 test/MonadCont.hs

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 0988e53..361477f 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -124,9 +124,9 @@ jobs:
           name: ${{ matrix.os }}-${{ matrix.ghc }}-plan.json
           path: mtl-*/dist-newstyle/cache/plan.json
 
-#       - name: Test
-#         run: |
-#           cabal --enable-tests --test-show-details=direct all
+      - name: Test
+        run: |
+          cabal test
 
       - name: Haddock
         run: |
@@ -166,6 +166,10 @@ jobs:
           # build
           stack build
 
+      - name: Test
+        run: |
+          stack test
+
   mhs:
     name: "MicroHS ${{ matrix.mhs }}"
     runs-on: ubuntu-latest
@@ -196,3 +200,8 @@ jobs:
         run: |
           cd mtl
           mcabal -r install
+
+      - name: test
+        run: |
+          cd mtl
+          mcabal test
diff --git a/Control/Monad/Cont/Class.hs b/Control/Monad/Cont/Class.hs
index 6bc4d78..9d85be6 100644
--- a/Control/Monad/Cont/Class.hs
+++ b/Control/Monad/Cont/Class.hs
@@ -114,12 +114,7 @@ class Monad m => MonadCont (m :: Type -> Type) where
     {-# MINIMAL callCC #-}
 
 -- | @since 2.3.1
-#ifdef __MHS__
--- The ContT type is not polykinded with mhs.
 instance MonadCont (ContT r m) where
-#else
-instance forall k (r :: k) (m :: (k -> Type)) . MonadCont (ContT r m) where
-#endif
     callCC = ContT.callCC
 
 -- ---------------------------------------------------------------------------
diff --git a/mtl.cabal b/mtl.cabal
index 0fcd9d3..1d19a37 100644
--- a/mtl.cabal
+++ b/mtl.cabal
@@ -24,7 +24,9 @@ extra-source-files:
 extra-doc-files:
   CHANGELOG.markdown
 
-tested-with: GHC ==8.10 || ==9.2 || ==9.8 || ==9.10 || ==9.12, MHS ==0.14.15.0
+tested-with:
+  , GHC ==8.10 || ==9.2 || ==9.8 || ==9.10 || ==9.12 || ==9.14
+  , MHS ==0.16.0.0
 
 source-repository head
   type: git
@@ -67,3 +69,10 @@ Library
     -Wmissing-export-lists
 
   default-language: Haskell2010
+
+test-suite MonadCont
+  type: exitcode-stdio-1.0
+  hs-source-dirs: test
+  main-is: MonadCont.hs
+  default-language: Haskell2010
+  build-depends: base, mtl, transformers
diff --git a/test/MonadCont.hs b/test/MonadCont.hs
new file mode 100644
index 0000000..c657ab8
--- /dev/null
+++ b/test/MonadCont.hs
@@ -0,0 +1,19 @@
+{-# LANGUAGE CPP #-}
+{-# LANGUAGE DataKinds #-}
+
+{-# OPTIONS_GHC -Wno-unused-binds #-}
+
+module Main (main) where
+
+import Control.Monad.Trans.Cont (ContT)
+import Control.Monad.Cont.Class (MonadCont (callCC))
+import Data.Proxy (Proxy)
+
+#ifdef __GLASGOW_HASKELL__
+-- Test that MonadCont is possible with polykinded ContT
+x :: (ContT 42 Proxy) ()
+x = callCC $ \_ -> return ()
+#endif
+
+main :: IO ()
+main = return ()