Move non-GHC2021 extensions in a separate section

core/src/Streamly/Internal/Data/Array/Type.hs

@@ -1,4 +1,8 @@
 {-# LANGUAGE CPP #-}
+{-# LANGUAGE TypeFamilies #-}
+-- Must come after TypeFamilies, otherwise it is re-enabled.
+-- MonoLocalBinds enabled by TypeFamilies causes perf regressions in general.
+{-# LANGUAGE NoMonoLocalBinds #-}
 -- |
 -- Module      : Streamly.Internal.Data.Array.Type
 -- Copyright   : (c) 2020 Composewell Technologies

core/src/Streamly/Internal/Data/IsMap.hs

@@ -1,3 +1,7 @@
+{-# LANGUAGE TypeFamilies #-}
+-- Must come after TypeFamilies, otherwise it is re-enabled.
+-- MonoLocalBinds enabled by TypeFamilies causes perf regressions in general.
+{-# LANGUAGE NoMonoLocalBinds #-}
 -- |
 -- Module      : Streamly.Internal.Data.IsMap
 -- Copyright   : (c) 2022 Composewell Technologies

core/src/Streamly/Internal/Data/Stream/Type.hs

@@ -1,5 +1,11 @@
 {-# LANGUAGE CPP #-}
+{-# LANGUAGE PatternSynonyms #-}
+{-# LANGUAGE TypeFamilies #-}
+-- Must come after TypeFamilies, otherwise it is re-enabled.
+-- MonoLocalBinds enabled by TypeFamilies causes perf regressions in general.
+{-# LANGUAGE NoMonoLocalBinds #-}
 {-# LANGUAGE UndecidableInstances #-}
+{-# LANGUAGE ViewPatterns #-}
 
 -- |
 -- Module      : Streamly.Internal.Data.Stream.Type

core/src/Streamly/Internal/Data/StreamK/Type.hs

@@ -1,4 +1,8 @@
 {-# LANGUAGE CPP #-}
+{-# LANGUAGE TypeFamilies #-}
+-- Must come after TypeFamilies, otherwise it is re-enabled.
+-- MonoLocalBinds enabled by TypeFamilies causes perf regressions in general.
+{-# LANGUAGE NoMonoLocalBinds #-}
 {-# LANGUAGE UndecidableInstances #-}
 -- |
 -- Module      : Streamly.Internal.Data.StreamK.Type

core/src/Streamly/Internal/Data/Time/Units.hs

@@ -1,7 +1,3 @@
-{-# LANGUAGE DataKinds #-}
-{-# LANGUAGE PolyKinds #-}
-{-# LANGUAGE UnboxedTuples #-}
-
 -- |
 -- Module      : Streamly.Internal.Data.Time.Units
 -- Copyright   : (c) 2019 Composewell Technologies

core/src/Streamly/Internal/Data/Unbox.hs

@@ -1,5 +1,8 @@
 {-# LANGUAGE DataKinds #-}
-{-# LANGUAGE DefaultSignatures #-}
+{-# LANGUAGE TypeFamilies #-}
+-- Must come after TypeFamilies, otherwise it is re-enabled.
+-- MonoLocalBinds enabled by TypeFamilies causes perf regressions in general.
+{-# LANGUAGE NoMonoLocalBinds #-}
 {-# LANGUAGE UnboxedTuples #-}
 {-# LANGUAGE UndecidableInstances #-}
 

core/streamly-core.cabal

@@ -218,8 +218,6 @@ common compile-options
 common default-extensions
     default-extensions:
         BangPatterns
-        CApiFFI
-        CPP
         ConstraintKinds
         DeriveDataTypeable
         DeriveGeneric
@@ -230,24 +228,29 @@ common default-extensions
         GeneralizedNewtypeDeriving
         InstanceSigs
         KindSignatures
-        LambdaCase
-        MagicHash
         MultiParamTypeClasses
-        PatternSynonyms
         RankNTypes
-        RecordWildCards
         ScopedTypeVariables
         StandaloneDeriving
         TupleSections
         TypeApplications
-        TypeFamilies
         TypeOperators
-        ViewPatterns
 
+        -- Not GHC2021
+        CApiFFI
+        CPP
+        DefaultSignatures
+        LambdaCase
+        MagicHash
+        RecordWildCards
+
+        -- TypeFamilies is required by IsList, IsMap type classes and
+        -- Unbox generic deriving code.
+        -- TypeFamilies
         -- MonoLocalBinds, enabled by TypeFamilies, causes performance
         -- regressions. Disable it. This must come after TypeFamilies,
         -- otherwise TypeFamilies will enable it again.
-        NoMonoLocalBinds
+        -- NoMonoLocalBinds
 
         -- UndecidableInstances -- Does not show any perf impact
         -- UnboxedTuples        -- interferes with (#.)

src/Streamly/Internal/Data/IsMap/HashMap.hs

@@ -1,3 +1,8 @@
+{-# LANGUAGE TypeFamilies #-}
+-- Must come after TypeFamilies, otherwise it is re-enabled.
+-- MonoLocalBinds enabled by TypeFamilies causes perf regressions in general.
+{-# LANGUAGE NoMonoLocalBinds #-}
+
 {-# OPTIONS_GHC -Wno-orphans #-}
 
 -- |

src/Streamly/Internal/Data/Stream/IsStream/Expand.hs

@@ -1,3 +1,8 @@
+{-# LANGUAGE TypeFamilies #-}
+-- Must come after TypeFamilies, otherwise it is re-enabled.
+-- MonoLocalBinds enabled by TypeFamilies causes perf regressions in general.
+{-# LANGUAGE NoMonoLocalBinds #-}
+
 {-# OPTIONS_GHC -Wno-deprecations #-}
 
 -- |

src/Streamly/Internal/Data/Stream/Serial.hs

@@ -1,4 +1,9 @@
+{-# LANGUAGE TypeFamilies #-}
+-- Must come after TypeFamilies, otherwise it is re-enabled.
+-- MonoLocalBinds enabled by TypeFamilies causes perf regressions in general.
+{-# LANGUAGE NoMonoLocalBinds #-}
 {-# LANGUAGE UndecidableInstances #-}
+
 {-# OPTIONS_GHC -Wno-deprecations #-}
 {-# OPTIONS_GHC -Wno-redundant-constraints #-}
 

src/Streamly/Internal/Data/Stream/Zip.hs

@@ -1,4 +1,9 @@
+{-# LANGUAGE TypeFamilies #-}
+-- Must come after TypeFamilies, otherwise it is re-enabled.
+-- MonoLocalBinds enabled by TypeFamilies causes perf regressions in general.
+{-# LANGUAGE NoMonoLocalBinds #-}
 {-# LANGUAGE UndecidableInstances #-}
+
 {-# OPTIONS_GHC -Wno-deprecations #-}
 
 -- |

streamly.cabal

@@ -294,8 +294,6 @@ common compile-options
 common default-extensions
     default-extensions:
         BangPatterns
-        CApiFFI
-        CPP
         ConstraintKinds
         DeriveDataTypeable
         DeriveGeneric
@@ -306,23 +304,25 @@ common default-extensions
         GeneralizedNewtypeDeriving
         InstanceSigs
         KindSignatures
-        LambdaCase
-        MagicHash
         MultiParamTypeClasses
-        PatternSynonyms
         RankNTypes
-        RecordWildCards
         ScopedTypeVariables
         TupleSections
         TypeApplications
-        TypeFamilies
         TypeOperators
-        ViewPatterns
 
+        -- Not GHC2021
+        CApiFFI
+        CPP
+        LambdaCase
+        MagicHash
+        RecordWildCards
+
+        -- TypeFamilies -- required by IsHashMap type class
         -- MonoLocalBinds, enabled by TypeFamilies, causes performance
         -- regressions. Disable it. This must come after TypeFamilies,
         -- otherwise TypeFamilies will enable it again.
-        NoMonoLocalBinds
+        -- NoMonoLocalBinds
 
         -- UndecidableInstances -- Does not show any perf impact
         -- UnboxedTuples        -- interferes with (#.)