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.. _release-8-10-1:
Release notes for version 8.10.1
===============================
The significant changes to the various parts of the compiler are listed in the
following sections.
Highlights
----------
Full details
------------
Language
~~~~~~~~
- Kind variables are no longer implicitly quantified when an explicit ``forall`` is used, see
`GHC proposal #24
<https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0024-no-kind-vars.rst>`__.
:ghc-flag:`-Wimplicit-kind-vars` is now obsolete.
- Kind variables are no longer implicitly quantified in constructor declarations: ::
data T a = T1 (S (a :: k) | forall (b::k). T2 (S b) -- no longer accepted
data T (a :: k) = T1 (S (a :: k) | forall (b::k). T2 (S b) -- still accepted
- Implicitly quantified kind variables are no longer put in front of other variables: ::
f :: Proxy (a :: k) -> Proxy (b :: j)
ghci> :t +v f -- old order:
f :: forall k j (a :: k) (b :: j). Proxy a -> Proxy b
ghci> :t +v f -- new order:
f :: forall k (a :: k) j (b :: j). Proxy a -> Proxy b
This is a breaking change for users of :extension:`TypeApplications`.
- In type synonyms and type family equations, free variables on the RHS are no longer
implicitly quantified unless used in an outermost kind annotation: ::
type T = Just (Nothing :: Maybe a) -- no longer accepted
type T = Just Nothing :: Maybe (Maybe a) -- still accepted
- GHC now parses visible, dependent quantifiers (as proposed in
`GHC proposal 35
<https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0035-forall-arrow.rst>`__),
such as the following: ::
data Proxy :: forall k -> k -> Type
See the `section on explicit kind quantification
<#explicit-kind-quantification>`__ for more details.
Compiler
~~~~~~~~
- Add new flags :ghc-flag:`-Wunused-record-wildcards` and
:ghc-flag:`-Wredundant-record-wildcards` which warn users when they have
redundant or unused uses of a record wildcard match.
- Calls to `memset` and `memcpy` are now unrolled more aggressively
and the produced code is more efficient on `x86_64` with added
support for 64-bit `MOV`s. In particular, `setByteArray#` and
`copyByteArray#` calls that were not optimized before, now will
be. See :ghc-ticket:`16052`.
- GHC's runtime linker no longer uses global state. This allows programs
that use the GHC API to safely use multiple GHC sessions in a single
process, as long as there are no native dependencies that rely on
global state.
Runtime system
~~~~~~~~~~~~~~
Template Haskell
~~~~~~~~~~~~~~~~
- The ``Lift`` typeclass is now levity-polymorphic and has a ``liftTyped``
method. Previously disallowed instances for unboxed tuples, unboxed sums, an
primitive unboxed types have also been added. Finally, the code generated by
:ghc-flags:`-XDeriveLift` has been simplified to take advantage of expression
quotations.
``ghc-prim`` library
~~~~~~~~~~~~~~~~~~~~
- Add new `bitReverse#` primops that, for a `Word` of 8, 16, 32 or 64 bits,
reverse the order of its bits e.g. `0b110001` becomes `0b100011`.
These primitives use optimized machine instructions when available.
``ghc`` library
~~~~~~~~~~~~~~~
``base`` library
~~~~~~~~~~~~~~~~
Build system
~~~~~~~~~~~~
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/containers/containers.cabal: Dependency of ``ghc`` library
libraries/deepseq/deepseq.cabal: Dependency of ``ghc`` library
libraries/directory/directory.cabal: Dependency of ``ghc`` 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/libiserv/libiserv.cabal: Internal compiler 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
|
