[Git][ghc/ghc][master] base: Define Semigroup and Monoid instances for lazy ST

Marge Bot pushed to branch master at Glasgow Haskell Compiler / GHC Commits: c32de3b0 by Johan Förberg at 2025-12-15T02:36:03-05:00 base: Define Semigroup and Monoid instances for lazy ST CLC proposal: https://github.com/haskell/core-libraries-committee/issues/374 Fixes #26581 - - - - - 6 changed files: - libraries/base/changelog.md - libraries/ghc-internal/src/GHC/Internal/Control/Monad/ST/Lazy/Imp.hs - testsuite/tests/interface-stability/base-exports.stdout - testsuite/tests/interface-stability/base-exports.stdout-javascript-unknown-ghcjs - testsuite/tests/interface-stability/base-exports.stdout-mingw32 - testsuite/tests/interface-stability/base-exports.stdout-ws-32 Changes: ===================================== libraries/base/changelog.md ===================================== @@ -14,6 +14,7 @@ * Remove extra laziness from `Data.Bifunctor.Bifunctor` instances for all tuples to have the same laziness as their `Data.Functor.Functor` counterparts (i.e. they became more strict than before) ([CLC proposal #339](https://github.com/haskell/core-libraries-committee/issues/339)) * Adjust the strictness of `Data.List.iterate'` to be more reasonable: every element of the output list is forced to WHNF when the `(:)` containing it is forced. ([CLC proposal #335)](https://github.com/haskell/core-libraries-committee/issues/335) * Add `nubOrd` / `nubOrdBy` to `Data.List` and `Data.List.NonEmpty`. ([CLC proposal #336](https://github.com/haskell/core-libraries-committee/issues/336)) + * Add `Semigroup` and `Monoid` instances for `Control.Monad.ST.Lazy`. ([CLC proposal #374](https://github.com/haskell/core-libraries-committee/issues/374)) ## 4.22.0.0 *TBA* * Shipped with GHC 9.14.1 ===================================== libraries/ghc-internal/src/GHC/Internal/Control/Monad/ST/Lazy/Imp.hs ===================================== @@ -214,6 +214,14 @@ fixST m = ST (\ s -> instance MonadFix (ST s) where mfix = fixST +-- | @since base-4.23.0.0 +instance Semigroup a => Semigroup (ST s a) where + (<>) = liftA2 (<>) + +-- | @since base-4.23.0.0 +instance Monoid a => Monoid (ST s a) where + mempty = pure mempty + -- --------------------------------------------------------------------------- -- Strict <--> Lazy ===================================== testsuite/tests/interface-stability/base-exports.stdout ===================================== @@ -11318,6 +11318,7 @@ instance forall a k (b :: k). GHC.Internal.Base.Monoid a => GHC.Internal.Base.Mo instance forall a. GHC.Internal.Base.Monoid a => GHC.Internal.Base.Monoid (GHC.Internal.Conc.Sync.STM a) -- Defined in ‘GHC.Internal.Conc.Sync’ instance GHC.Internal.Base.Monoid GHC.Internal.Exception.Context.ExceptionContext -- Defined in ‘GHC.Internal.Exception.Context’ instance forall a s. GHC.Internal.Base.Monoid a => GHC.Internal.Base.Monoid (GHC.Internal.ST.ST s a) -- Defined in ‘GHC.Internal.ST’ +instance forall a s. GHC.Internal.Base.Monoid a => GHC.Internal.Base.Monoid (GHC.Internal.Control.Monad.ST.Lazy.Imp.ST s a) -- Defined in ‘GHC.Internal.Control.Monad.ST.Lazy.Imp’ instance GHC.Internal.Base.Monoid Data.Array.Byte.ByteArray -- Defined in ‘Data.Array.Byte’ instance forall a. GHC.Internal.Bits.FiniteBits a => GHC.Internal.Base.Monoid (GHC.Internal.Data.Bits.And a) -- Defined in ‘GHC.Internal.Data.Bits’ instance forall a. GHC.Internal.Bits.FiniteBits a => GHC.Internal.Base.Monoid (GHC.Internal.Data.Bits.Iff a) -- Defined in ‘GHC.Internal.Data.Bits’ @@ -11372,6 +11373,7 @@ instance forall a k (b :: k). GHC.Internal.Base.Semigroup a => GHC.Internal.Base instance forall a. GHC.Internal.Base.Semigroup a => GHC.Internal.Base.Semigroup (GHC.Internal.Conc.Sync.STM a) -- Defined in ‘GHC.Internal.Conc.Sync’ instance GHC.Internal.Base.Semigroup GHC.Internal.Exception.Context.ExceptionContext -- Defined in ‘GHC.Internal.Exception.Context’ instance forall a s. GHC.Internal.Base.Semigroup a => GHC.Internal.Base.Semigroup (GHC.Internal.ST.ST s a) -- Defined in ‘GHC.Internal.ST’ +instance forall a s. GHC.Internal.Base.Semigroup a => GHC.Internal.Base.Semigroup (GHC.Internal.Control.Monad.ST.Lazy.Imp.ST s a) -- Defined in ‘GHC.Internal.Control.Monad.ST.Lazy.Imp’ instance GHC.Internal.Base.Semigroup Data.Array.Byte.ByteArray -- Defined in ‘Data.Array.Byte’ instance forall a. GHC.Internal.Bits.Bits a => GHC.Internal.Base.Semigroup (GHC.Internal.Data.Bits.And a) -- Defined in ‘GHC.Internal.Data.Bits’ instance forall a. GHC.Internal.Bits.FiniteBits a => GHC.Internal.Base.Semigroup (GHC.Internal.Data.Bits.Iff a) -- Defined in ‘GHC.Internal.Data.Bits’ ===================================== testsuite/tests/interface-stability/base-exports.stdout-javascript-unknown-ghcjs ===================================== @@ -14364,6 +14364,7 @@ instance forall a k (b :: k). GHC.Internal.Base.Monoid a => GHC.Internal.Base.Mo instance forall a. GHC.Internal.Base.Monoid a => GHC.Internal.Base.Monoid (GHC.Internal.Conc.Sync.STM a) -- Defined in ‘GHC.Internal.Conc.Sync’ instance GHC.Internal.Base.Monoid GHC.Internal.Exception.Context.ExceptionContext -- Defined in ‘GHC.Internal.Exception.Context’ instance forall a s. GHC.Internal.Base.Monoid a => GHC.Internal.Base.Monoid (GHC.Internal.ST.ST s a) -- Defined in ‘GHC.Internal.ST’ +instance forall a s. GHC.Internal.Base.Monoid a => GHC.Internal.Base.Monoid (GHC.Internal.Control.Monad.ST.Lazy.Imp.ST s a) -- Defined in ‘GHC.Internal.Control.Monad.ST.Lazy.Imp’ instance GHC.Internal.Base.Monoid Data.Array.Byte.ByteArray -- Defined in ‘Data.Array.Byte’ instance forall a. GHC.Internal.Bits.FiniteBits a => GHC.Internal.Base.Monoid (GHC.Internal.Data.Bits.And a) -- Defined in ‘GHC.Internal.Data.Bits’ instance forall a. GHC.Internal.Bits.FiniteBits a => GHC.Internal.Base.Monoid (GHC.Internal.Data.Bits.Iff a) -- Defined in ‘GHC.Internal.Data.Bits’ @@ -14415,6 +14416,7 @@ instance forall a k (b :: k). GHC.Internal.Base.Semigroup a => GHC.Internal.Base instance forall a. GHC.Internal.Base.Semigroup a => GHC.Internal.Base.Semigroup (GHC.Internal.Conc.Sync.STM a) -- Defined in ‘GHC.Internal.Conc.Sync’ instance GHC.Internal.Base.Semigroup GHC.Internal.Exception.Context.ExceptionContext -- Defined in ‘GHC.Internal.Exception.Context’ instance forall a s. GHC.Internal.Base.Semigroup a => GHC.Internal.Base.Semigroup (GHC.Internal.ST.ST s a) -- Defined in ‘GHC.Internal.ST’ +instance forall a s. GHC.Internal.Base.Semigroup a => GHC.Internal.Base.Semigroup (GHC.Internal.Control.Monad.ST.Lazy.Imp.ST s a) -- Defined in ‘GHC.Internal.Control.Monad.ST.Lazy.Imp’ instance GHC.Internal.Base.Semigroup Data.Array.Byte.ByteArray -- Defined in ‘Data.Array.Byte’ instance forall a. GHC.Internal.Bits.Bits a => GHC.Internal.Base.Semigroup (GHC.Internal.Data.Bits.And a) -- Defined in ‘GHC.Internal.Data.Bits’ instance forall a. GHC.Internal.Bits.FiniteBits a => GHC.Internal.Base.Semigroup (GHC.Internal.Data.Bits.Iff a) -- Defined in ‘GHC.Internal.Data.Bits’ ===================================== testsuite/tests/interface-stability/base-exports.stdout-mingw32 ===================================== @@ -11580,6 +11580,7 @@ instance forall a k (b :: k). GHC.Internal.Base.Monoid a => GHC.Internal.Base.Mo instance forall a. GHC.Internal.Base.Monoid a => GHC.Internal.Base.Monoid (GHC.Internal.Conc.Sync.STM a) -- Defined in ‘GHC.Internal.Conc.Sync’ instance GHC.Internal.Base.Monoid GHC.Internal.Exception.Context.ExceptionContext -- Defined in ‘GHC.Internal.Exception.Context’ instance forall a s. GHC.Internal.Base.Monoid a => GHC.Internal.Base.Monoid (GHC.Internal.ST.ST s a) -- Defined in ‘GHC.Internal.ST’ +instance forall a s. GHC.Internal.Base.Monoid a => GHC.Internal.Base.Monoid (GHC.Internal.Control.Monad.ST.Lazy.Imp.ST s a) -- Defined in ‘GHC.Internal.Control.Monad.ST.Lazy.Imp’ instance GHC.Internal.Base.Monoid Data.Array.Byte.ByteArray -- Defined in ‘Data.Array.Byte’ instance forall a. GHC.Internal.Bits.FiniteBits a => GHC.Internal.Base.Monoid (GHC.Internal.Data.Bits.And a) -- Defined in ‘GHC.Internal.Data.Bits’ instance forall a. GHC.Internal.Bits.FiniteBits a => GHC.Internal.Base.Monoid (GHC.Internal.Data.Bits.Iff a) -- Defined in ‘GHC.Internal.Data.Bits’ @@ -11632,6 +11633,7 @@ instance forall a k (b :: k). GHC.Internal.Base.Semigroup a => GHC.Internal.Base instance forall a. GHC.Internal.Base.Semigroup a => GHC.Internal.Base.Semigroup (GHC.Internal.Conc.Sync.STM a) -- Defined in ‘GHC.Internal.Conc.Sync’ instance GHC.Internal.Base.Semigroup GHC.Internal.Exception.Context.ExceptionContext -- Defined in ‘GHC.Internal.Exception.Context’ instance forall a s. GHC.Internal.Base.Semigroup a => GHC.Internal.Base.Semigroup (GHC.Internal.ST.ST s a) -- Defined in ‘GHC.Internal.ST’ +instance forall a s. GHC.Internal.Base.Semigroup a => GHC.Internal.Base.Semigroup (GHC.Internal.Control.Monad.ST.Lazy.Imp.ST s a) -- Defined in ‘GHC.Internal.Control.Monad.ST.Lazy.Imp’ instance GHC.Internal.Base.Semigroup Data.Array.Byte.ByteArray -- Defined in ‘Data.Array.Byte’ instance forall a. GHC.Internal.Bits.Bits a => GHC.Internal.Base.Semigroup (GHC.Internal.Data.Bits.And a) -- Defined in ‘GHC.Internal.Data.Bits’ instance forall a. GHC.Internal.Bits.FiniteBits a => GHC.Internal.Base.Semigroup (GHC.Internal.Data.Bits.Iff a) -- Defined in ‘GHC.Internal.Data.Bits’ ===================================== testsuite/tests/interface-stability/base-exports.stdout-ws-32 ===================================== @@ -11318,6 +11318,7 @@ instance forall a k (b :: k). GHC.Internal.Base.Monoid a => GHC.Internal.Base.Mo instance forall a. GHC.Internal.Base.Monoid a => GHC.Internal.Base.Monoid (GHC.Internal.Conc.Sync.STM a) -- Defined in ‘GHC.Internal.Conc.Sync’ instance GHC.Internal.Base.Monoid GHC.Internal.Exception.Context.ExceptionContext -- Defined in ‘GHC.Internal.Exception.Context’ instance forall a s. GHC.Internal.Base.Monoid a => GHC.Internal.Base.Monoid (GHC.Internal.ST.ST s a) -- Defined in ‘GHC.Internal.ST’ +instance forall a s. GHC.Internal.Base.Monoid a => GHC.Internal.Base.Monoid (GHC.Internal.Control.Monad.ST.Lazy.Imp.ST s a) -- Defined in ‘GHC.Internal.Control.Monad.ST.Lazy.Imp’ instance GHC.Internal.Base.Monoid Data.Array.Byte.ByteArray -- Defined in ‘Data.Array.Byte’ instance forall a. GHC.Internal.Bits.FiniteBits a => GHC.Internal.Base.Monoid (GHC.Internal.Data.Bits.And a) -- Defined in ‘GHC.Internal.Data.Bits’ instance forall a. GHC.Internal.Bits.FiniteBits a => GHC.Internal.Base.Monoid (GHC.Internal.Data.Bits.Iff a) -- Defined in ‘GHC.Internal.Data.Bits’ @@ -11372,6 +11373,7 @@ instance forall a k (b :: k). GHC.Internal.Base.Semigroup a => GHC.Internal.Base instance forall a. GHC.Internal.Base.Semigroup a => GHC.Internal.Base.Semigroup (GHC.Internal.Conc.Sync.STM a) -- Defined in ‘GHC.Internal.Conc.Sync’ instance GHC.Internal.Base.Semigroup GHC.Internal.Exception.Context.ExceptionContext -- Defined in ‘GHC.Internal.Exception.Context’ instance forall a s. GHC.Internal.Base.Semigroup a => GHC.Internal.Base.Semigroup (GHC.Internal.ST.ST s a) -- Defined in ‘GHC.Internal.ST’ +instance forall a s. GHC.Internal.Base.Semigroup a => GHC.Internal.Base.Semigroup (GHC.Internal.Control.Monad.ST.Lazy.Imp.ST s a) -- Defined in ‘GHC.Internal.Control.Monad.ST.Lazy.Imp’ instance GHC.Internal.Base.Semigroup Data.Array.Byte.ByteArray -- Defined in ‘Data.Array.Byte’ instance forall a. GHC.Internal.Bits.Bits a => GHC.Internal.Base.Semigroup (GHC.Internal.Data.Bits.And a) -- Defined in ‘GHC.Internal.Data.Bits’ instance forall a. GHC.Internal.Bits.FiniteBits a => GHC.Internal.Base.Semigroup (GHC.Internal.Data.Bits.Iff a) -- Defined in ‘GHC.Internal.Data.Bits’ View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/c32de3b005034f3c17c849d395f46a63... -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/c32de3b005034f3c17c849d395f46a63... You're receiving this email because of your account on gitlab.haskell.org.