WIP: Preliminary ghc 9.14 support

cabal.project

@@ -14,9 +14,9 @@ repository cardano-haskell-packages
 -- update either of these.
 index-state:
   -- Bump both the following dates if you need newer packages from Hackage
-  , hackage.haskell.org 2025-09-21T21:31:06Z
+  , hackage.haskell.org 2026-01-05T22:32:33Z
   -- Bump this if you need newer packages from CHaP
-  , cardano-haskell-packages 2025-09-18T12:21:32Z
+  , cardano-haskell-packages 2026-01-05T11:07:19Z
 
 packages: cardano-constitution
           plutus-benchmark
@@ -75,16 +75,148 @@ source-repository-package
   tag: e814b9171398cbdfecdc6823067156a7e9fc76a3
 
 allow-newer:
-  -- https://github.com/tweag/HaskellR/pull/420
-  , inline-r:singletons-th
-  , inline-r:aeson
-  , inline-r:text
-  , inline-r:template-haskell
-  , inline-r:deepseq
-  , inline-r:bytestring
-  , inline-r:containers
-  , inline-r:primitive
+  -- https://github.com/phadej/vec/issues/121
+  ral:QuickCheck,
+  fin:QuickCheck,
+  bin:QuickCheck,
 
 -- https://github.com/IntersectMBO/plutus/pull/7236
 constraints: setup.optparse-applicative >=0.19.0.0
 allow-newer: turtle:optparse-applicative
+
+if impl (ghc >= 9.14)
+  -- https://github.com/snowleopard/alga/issues/322
+  source-repository-package
+    type: git
+    location: https://github.com/snowleopard/alga/
+    tag: d4e43fb42db05413459fb2df493361d5a666588a
+
+if impl (ghc >= 9.14)
+  constraints:
+    -- Newest version causes Arbitrary instance clashes in quickcheck-instances.
+    , QuickCheck < 2.17.0.0
+    , brick >= 2.10
+
+  allow-newer:
+    -- https://github.com/haskell/aeson/issues/1155
+    , aeson:OneTuple
+    , aeson:containers
+    , aeson:data-fix
+    , aeson:indexed-traversable
+    , aeson:scientific
+    , aeson:semialign
+    , aeson:template-haskell
+    , aeson:text-iso8601
+    , aeson:these
+    , aeson:time
+    , aeson:time-compat
+
+    -- https://github.com/simonmar/async/issues/175
+    , async:base
+
+    -- https://github.com/jtdaugherty/brick/issues/543
+    , brick:base
+
+    -- https://github.com/well-typed/cborg/issues/373
+    , cborg:base
+    , cborg:containers
+    , cborg:ghc-prim
+
+    -- https://github.com/hedgehogqa/haskell-hedgehog/issues/566
+    , hedgehog:bytestring
+    , hedgehog:template-haskell
+    , hedgehog:time
+    , hedgehog-fn:hedgehog
+
+    -- https://github.com/well-typed/cborg/issues/373
+    , serialise:base
+    , serialise:containers
+    , serialise:time
+
+
+-- cabal-allow-newer
+if impl (ghc >= 9.14)
+  allow-newer:
+    , OneTuple:base
+    , QuickCheck:base
+    , bin:base
+    , binary:containers
+    , binary-orphans:base
+    , boring:base
+    , config-ini:containers
+    , constraints-extras:base
+    , constraints-extras:template-haskell
+    , containers:base
+    , containers:template-haskell
+    , dec:base
+    , deepseq:base
+    , dependent-map:containers
+    , deriving-compat:containers
+    , deriving-compat:template-haskell
+    , dictionary-sharing:containers
+    , directory:time
+    , filepath:deepseq
+    , fin:base
+    , fin:universe-base
+    , foldl:containers
+    , free:mtl
+    , free:template-haskell
+    , indexed-traversable:base
+    , indexed-traversable:containers
+    , indexed-traversable-instances:base
+    , lens:containers
+    , lens:free
+    , lens:template-haskell
+    , list-t:foldl
+    , microlens-th:containers
+    , microlens-th:template-haskell
+    , microstache:base
+    , microstache:containers
+    , monoidal-containers:base
+    , monoidal-containers:containers
+    , nonempty-vector:base
+    , nothunks:time
+    , ordered-containers:containers
+    , os-string:template-haskell
+    , parsec:mtl
+    , parsec:text
+    , quickcheck-instances:QuickCheck
+    , quickcheck-instances:base
+    , quickcheck-instances:containers
+    , ral:base
+    , recursion-schemes:base-orphans
+    , recursion-schemes:containers
+    , recursion-schemes:template-haskell
+    , semialign:base
+    , semialign:containers
+    , singletons:base
+    , singletons-th:base
+    , singletons-th:singletons
+    , singletons-th:template-haskell
+    , singletons-th:th-desugar
+    , singletons-th:th-orphans
+    , size-based:template-haskell
+    , some:base
+    , text:template-haskell
+    , text-iso8601:time
+    , th-desugar:template-haskell
+    , th-expand-syns:base
+    , th-expand-syns:containers
+    , th-expand-syns:template-haskell
+    , th-orphans:template-haskell
+    , these:base
+    , time-compat:base
+    , time-compat:deepseq
+    , time-compat:time
+    , tree-diff:QuickCheck
+    , tree-diff:base
+    , tree-diff:containers
+    , tree-diff:time
+    , turtle:containers
+    , turtle:time
+    , universe-base:base
+    , universe-base:containers
+    , unix:time
+    , uuid-types:template-haskell
+    , vector-th-unbox:base
+    , vector-th-unbox:template-haskell

plutus-core/plutus-core.cabal

@@ -734,7 +734,7 @@ executable plutus
     , singletons-th
     , text
     , text-zipper
-    , vty                    ^>=6.2
+    , vty                    ^>=6.5
     , vty-crossplatform      ^>=0.4
 
   ghc-options:        -O2 -threaded -rtsopts -with-rtsopts=-N

plutus-core/plutus-core/src/PlutusCore/Core/Instance/Eq.hs

@@ -1,3 +1,4 @@
+{-# LANGUAGE CPP                  #-}
 {-# LANGUAGE FlexibleInstances #-}
 {-# LANGUAGE RankNTypes #-}
 {-# LANGUAGE TypeApplications #-}
@@ -8,6 +9,7 @@
 {-# OPTIONS_GHC -fno-warn-orphans #-}
 
 -- | 'Eq' instances for core data types.
+
 module PlutusCore.Core.Instance.Eq () where
 
 import PlutusPrelude
@@ -55,15 +57,14 @@ deriving stock instance
   (GEq uni, Closed uni, uni `Everywhere` Eq, Eq ann)
   => Eq (Type TyDeBruijn uni ann)
 
-deriving stock instance
-  ( GEq uni
-  , Closed uni
-  , uni `Everywhere` Eq
-  , Eq fun
-  , Eq ann
-  , Eq (Term tyname name uni fun ann)
-  )
-  => Eq (Program tyname name uni fun ann)
+deriving stock instance (
+#if __GLASGOW_HASKELL__ < 914
+  -- These constraints are REQUIRED for ghc < 9.14 but REDUNDANT for ghc >= 9.14
+  -- See https://gitlab.haskell.org/ghc/ghc/-/issues/26381#note_637863
+  GEq uni, Closed uni, Eq fun,
+#endif
+  uni `Everywhere` Eq, Eq ann,
+                  Eq (Term tyname name uni fun ann)                  ) =>  Eq (Program tyname name uni fun ann)
 
 type EqRenameOf ren a = HasUniques a => a -> a -> EqRename ren
 

plutus-core/plutus-core/src/PlutusCore/Error.hs

@@ -1,3 +1,5 @@
+
+{-# LANGUAGE CPP #-}
 {-# LANGUAGE DeriveAnyClass #-}
 {-# LANGUAGE FlexibleInstances #-}
 {-# LANGUAGE FunctionalDependencies #-}
@@ -81,15 +83,16 @@ deriving stock instance
   => Show (NormCheckError tyname name uni fun ann)
 
 deriving stock instance
-  ( Eq (Term tyname name uni fun ann)
-  , Eq (Type tyname uni ann)
-  , GEq uni
-  , Closed uni
-  , uni `Everywhere` Eq
-  , Eq fun
-  , Eq ann
-  )
-  => Eq (NormCheckError tyname name uni fun ann)
+    ( Eq (Term tyname name uni fun ann)
+    , Eq (Type tyname uni ann)
+#if __GLASGOW_HASKELL__ < 914
+    -- These constraints are REQUIRED for ghc < 9.14 but REDUNDANT for ghc >= 9.14
+    -- See https://gitlab.haskell.org/ghc/ghc/-/issues/26381#note_637863
+    , GEq uni, Closed uni
+    , Eq fun
+#endif
+    , uni `Everywhere` Eq, Eq ann
+    ) => Eq (NormCheckError tyname name uni fun ann)
 
 {-| This is needed for nice kind/type checking error messages. In some cases the type checker knows
 the exact type that an expression has to have for type checking to succeed (see any of
@@ -156,16 +159,34 @@ data Error uni fun ann
   deriving stock (Generic, Functor)
 
 deriving stock instance
-  (Eq fun, Eq ann, Closed uni, Everywhere uni Eq, GEq uni, Eq ParserError)
-  => Eq (Error uni fun ann)
+    (Eq fun, Eq ann, Closed uni, Everywhere uni Eq, GEq uni
+#if __GLASGOW_HASKELL__ < 914
+    -- These constraints are REQUIRED for ghc < 9.14 but REDUNDANT for ghc >= 9.14
+    -- See https://gitlab.haskell.org/ghc/ghc/-/issues/26381#note_637863
+    , Eq ParserError
+#endif
+    ) =>
+        Eq (Error uni fun ann)
 
 deriving anyclass instance
-  (NFData fun, NFData ann, Closed uni, Everywhere uni NFData, NFData ParserError)
-  => NFData (Error uni fun ann)
+    (NFData fun, NFData ann, Closed uni, Everywhere uni NFData
+#if __GLASGOW_HASKELL__ < 914
+    -- These constraints are REQUIRED for ghc < 9.14 but REDUNDANT for ghc >= 9.14
+    -- See https://gitlab.haskell.org/ghc/ghc/-/issues/26381#note_637863
+    , NFData ParserError
+#endif
+    ) =>
+        NFData (Error uni fun ann)
 
 deriving stock instance
-  (Show fun, Show ann, Closed uni, Everywhere uni Show, GShow uni, Show ParserError)
-  => Show (Error uni fun ann)
+    (Show fun, Show ann, Closed uni, Everywhere uni Show, GShow uni
+#if __GLASGOW_HASKELL__ < 914
+    -- These constraints are REQUIRED for ghc < 9.14 but REDUNDANT for ghc >= 9.14
+    -- See https://gitlab.haskell.org/ghc/ghc/-/issues/26381#note_637863
+    , Show ParserError
+#endif
+    ) =>
+        Show (Error uni fun ann)
 
 instance Pretty SourcePos where
   pretty = pretty . sourcePosPretty

plutus-core/untyped-plutus-core/src/UntypedPlutusCore/Core/Instance/Eq.hs

@@ -1,3 +1,4 @@
+{-# LANGUAGE CPP #-}
 {-# LANGUAGE ConstraintKinds #-}
 {-# LANGUAGE FlexibleInstances #-}
 {-# LANGUAGE TypeOperators #-}
@@ -66,15 +67,15 @@ deriving stock instance
 
 instance HashableTermConstraints uni fun ann => Hashable (Term DeBruijn uni fun ann)
 
-deriving stock instance
-  ( GEq uni
-  , Closed uni
-  , uni `Everywhere` Eq
-  , Eq fun
-  , Eq ann
-  , Eq (Term name uni fun ann)
-  )
-  => Eq (Program name uni fun ann)
+deriving stock instance (
+#if __GLASGOW_HASKELL__ < 914
+  -- These constraints are REQUIRED for ghc < 9.14 but REDUNDANT for ghc >= 9.14
+  -- See https://gitlab.haskell.org/ghc/ghc/-/issues/26381#note_637863
+  GEq uni, Closed uni, Eq fun,
+#endif
+  uni `Everywhere` Eq, Eq ann,
+                  Eq (Term name uni fun ann)
+                  ) =>  Eq (Program name uni fun ann)
 
 -- | Check equality of two 'Term's.
 eqTermM

plutus-tx/src/PlutusTx/BuiltinList.hs

@@ -1,3 +1,5 @@
+{-# LANGUAGE CPP #-}
+
 {-# OPTIONS_GHC -Wno-unrecognised-pragmas #-}
 
 {-# HLINT ignore "Redundant if" #-}
@@ -283,9 +285,13 @@ reverse xs = revAppend xs empty
 
 -- | Plutus Tx version of 'Data.List.zip' for 'BuiltinList'.
 _zip
-  :: forall a b
-   . (MkNil a, MkNil b)
-  => BuiltinList a
+  :: forall a b .
+#if __GLASGOW_HASKELL__ < 914
+     -- These constraints are REQUIRED for ghc < 9.14 but REDUNDANT for ghc >= 9.14
+     -- See https://gitlab.haskell.org/ghc/ghc/-/issues/26381#note_637863
+     (MkNil a, MkNil b) =>
+#endif
+     BuiltinList a
   -> BuiltinList b
   -> BuiltinList (BuiltinPair a b)
 _zip = zipWith (curry BI.BuiltinPair)

plutus-tx/src/PlutusTx/Builtins/HasOpaque.hs

@@ -18,8 +18,7 @@ import PlutusCore.Pretty (Pretty (..))
 import PlutusTx.Base (id)
 import PlutusTx.Bool (Bool (..))
 import PlutusTx.Builtins.Internal
-  ( BuiltinArray
-  , BuiltinBLS12_381_G1_Element
+  ( BuiltinBLS12_381_G1_Element
   , BuiltinBLS12_381_G2_Element
   , BuiltinBLS12_381_MlResult
   , BuiltinByteString (..)
@@ -292,9 +291,22 @@ instance MkNil BuiltinData
 instance MkNil BuiltinValue
 instance MkNil BuiltinBLS12_381_G1_Element
 instance MkNil BuiltinBLS12_381_G2_Element
-instance MkNil a => MkNil (BuiltinList a)
-instance MkNil a => MkNil (BuiltinArray a)
-instance (MkNil a, MkNil b) => MkNil (BuiltinPair a b)
+
+instance
+#if __GLASGOW_HASKELL__ < 914
+         -- This constraint is REQUIRED for ghc < 9.14 but REDUNDANT for ghc >= 9.14
+         -- See https://gitlab.haskell.org/ghc/ghc/-/issues/26381#note_637863
+         (MkNil a) =>
+#endif
+         MkNil (BuiltinList a)
+
+instance
+#if __GLASGOW_HASKELL__ < 914
+         -- These constraints are REQUIRED for ghc < 9.14 but REDUNDANT for ghc >= 9.14
+         -- See https://gitlab.haskell.org/ghc/ghc/-/issues/26381#note_637863
+         (MkNil a, MkNil b) =>
+#endif
+         MkNil (BuiltinPair a b)
 
 instance (HasToOpaque a arep, MkNil arep) => HasToOpaque [a] (BuiltinList arep) where
   toOpaque = goList

plutus-tx/src/PlutusTx/Enum/TH.hs

@@ -50,7 +50,7 @@ deriveEnum name = do
     <$> instanceD
       (pure [])
       (pure instanceType)
-      [ funD 'succ (fmap (deriveSuccPred Succ) (zip cons (tail (Just <$> cons) ++ [Nothing])))
+      [ funD 'succ (fmap (deriveSuccPred Succ) (zip cons (drop 1 $ (Just <$> cons) ++ [Nothing])))
       , TH.pragInlD 'succ TH.Inlinable TH.FunLike TH.AllPhases
       , funD 'pred (fmap (deriveSuccPred Pred) (zip cons (Nothing : init (Just <$> cons))))
       , TH.pragInlD 'pred TH.Inlinable TH.FunLike TH.AllPhases