.. _release-9-8-1: Version 9.8.1 ============= Language ~~~~~~~~ Compiler ~~~~~~~~ - Added a new warning :ghc-flag:`-Wterm-variable-capture` that helps to make code compatible with the future extension ``RequiredTypeArguments``. - Rewrite rules now support a limited form of higher order matching when a pattern variable is applied to distinct locally bound variables. For example: :: forall f. foo (\x -> f x) Now matches: :: foo (\x -> x*2 + x) - GHC Proposal `#496 `_ has been implemented, allowing ``{..}`` syntax for constructors without fields, for consistency. This is convenient for TH code generation, as you can now uniformly use record wildcards regardless of number of fields. - Incoherent instance applications are no longer specialised. The previous implementation of specialisation resulted in nondeterministic instance resolution in certain cases, breaking the specification described in the documentation of the `INCOHERENT` pragma. See GHC ticket #22448 for further details. - Fix a bug in TH causing excessive calls to ``setNumCapabilities`` when ``-j`` is greater than ``-N``. See GHC ticket #23049. - The ``-Wno-⟨wflag⟩``, ``-Werror=⟨wflag⟩`` and ``-Wwarn=⟨wflag⟩`` options are now defined systematically for all warning groups (for example, ``-Wno-default``, ``-Werror=unused-binds`` and ``-Wwarn=all`` are now accepted). See :ref:`options-sanity`. - ``WARNING`` pragmas may now be annotated with a category, following `GHC proposal #541 `_, in which case they are controlled with new ``-Wx-⟨category⟩`` flags rather than :ghc-flag:`-Wdeprecations`. A new warning group :ghc-flag:`-Wextended-warnings` includes all such warnings regardless of category. See :ref:`warning-deprecated-pragma`. - GHC is now better at disambiguating record updates in the presence of duplicate record fields. The following program is now accepted :: {-# LANGUAGE DuplicateRecordFields #-} data R = MkR1 { foo :: Int } | MkR2 { bar :: Int } data S = MkS { foo :: Int, bar :: Int } blah x = x { foo = 5, bar = 6 } The point is that only the type S has a constructor with both fields "foo" and "bar", so this record update is unambiguous. GHCi ~~~~ Runtime system ~~~~~~~~~~~~~~ - On POSIX systems that support timerfd, RTS shutdown no longer has to wait for the next RTS 'tick' to occur before continuing the shutdown process. See #22692. ``base`` library ~~~~~~~~~~~~~~~~ - ``Data.Tuple`` now exports ``getSolo :: Solo a -> a``. ``ghc-prim`` library ~~~~~~~~~~~~~~~~~~~~ - Primitive pointer comparison functions are now levity-polymorphic, e.g. :: sameArray# :: forall {l} (a :: TYPE (BoxedRep l)). Array# a -> Array# a -> Int# This change affects the following functions: - ``sameArray#``, ``sameMutableArray#``, - ``sameSmallArray#``, ``sameSmallMutableArray#``, - ``sameMutVar#``, ``sameTVar#``, ``sameMVar#`` - ``sameIOPort#``, ``eqStableName#``. ``ghc`` library ~~~~~~~~~~~~~~~ ``ghc-heap`` library ~~~~~~~~~~~~~~~~~~~~ ``template-haskell`` library ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - The ``GadtC`` and ``RecGadtC`` constructors of the ``Con`` datatype now take non-empty lists of constructors. This means that the ``gadtC`` and ``recGadtC`` smart constructors also expect non-empty lists as arguments. - Record fields now belong to separate ``NameSpace``s, keyed by the parent of the record field. This is the name of the first constructor of the parent type, even if this constructor does not have the field in question. This change enables TemplateHaskell support for ``DuplicateRecordFields``. Included libraries ------------------ The package database provided with this distribution also contains a number of packages other than GHC itself. See the changelogs provided with these packages for further change information. .. ghc-package-list:: libraries/array/array.cabal: Dependency of ``ghc`` library libraries/base/base.cabal: Core library libraries/binary/binary.cabal: Dependency of ``ghc`` library libraries/bytestring/bytestring.cabal: Dependency of ``ghc`` library libraries/Cabal/Cabal/Cabal.cabal: Dependency of ``ghc-pkg`` utility libraries/Cabal/Cabal-syntax/Cabal-syntax.cabal: Dependency of ``ghc-pkg`` utility libraries/containers/containers/containers.cabal: Dependency of ``ghc`` library libraries/deepseq/deepseq.cabal: Dependency of ``ghc`` library libraries/directory/directory.cabal: Dependency of ``ghc`` library libraries/exceptions/exceptions.cabal: Dependency of ``ghc`` and ``haskeline`` library libraries/filepath/filepath.cabal: Dependency of ``ghc`` library compiler/ghc.cabal: The compiler itself libraries/ghci/ghci.cabal: The REPL interface libraries/ghc-boot/ghc-boot.cabal: Internal compiler library libraries/ghc-boot-th/ghc-boot-th.cabal: Internal compiler library libraries/ghc-compact/ghc-compact.cabal: Core library libraries/ghc-heap/ghc-heap.cabal: GHC heap-walking library libraries/ghc-prim/ghc-prim.cabal: Core library libraries/haskeline/haskeline.cabal: Dependency of ``ghci`` executable libraries/hpc/hpc.cabal: Dependency of ``hpc`` executable libraries/integer-gmp/integer-gmp.cabal: Core library libraries/mtl/mtl.cabal: Dependency of ``Cabal`` library libraries/parsec/parsec.cabal: Dependency of ``Cabal`` library libraries/pretty/pretty.cabal: Dependency of ``ghc`` library libraries/process/process.cabal: Dependency of ``ghc`` library libraries/stm/stm.cabal: Dependency of ``haskeline`` library libraries/template-haskell/template-haskell.cabal: Core library libraries/terminfo/terminfo.cabal: Dependency of ``haskeline`` library libraries/text/text.cabal: Dependency of ``Cabal`` library libraries/time/time.cabal: Dependency of ``ghc`` library libraries/transformers/transformers.cabal: Dependency of ``ghc`` library libraries/unix/unix.cabal: Dependency of ``ghc`` library libraries/Win32/Win32.cabal: Dependency of ``ghc`` library libraries/xhtml/xhtml.cabal: Dependency of ``haddock`` executable