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diff --git a/docs/users_guide/8.4.1-notes.rst b/docs/users_guide/8.4.1-notes.rst deleted file mode 100644 index 9b9d79ffd4..0000000000 --- a/docs/users_guide/8.4.1-notes.rst +++ /dev/null @@ -1,142 +0,0 @@ -.. _release-8-4-1: - -Release notes for version 8.4.1 -=============================== - -The significant changes to the various parts of the compiler are listed in the -following sections. There have also been numerous bug fixes and performance -improvements over the 8.2.1 release. - - -Highlights ----------- - -The highlights, since the 8.2.1 release, are: - -- Many, many bug fixes. - -Full details ------------- - -Language -~~~~~~~~ - -Compiler -~~~~~~~~ - -- The ``configure`` script now no longer accepts ``--with-TOOL`` flags (e.g. - ``--with-nm``, ``--with-ld``, etc.). Instead, these are taken from environment - variables, as is typical in ``autoconf`` scripts. For instance, - ``./configure --with-nm=/usr/local/bin/nm`` turns into - ``./configure NM=/usr/local/bin/nm``. - -- Derived ``Functor``, ``Foldable``, and ``Traversable`` instances are now - optimized when their last type parameters have phantom roles. - Specifically, :: - - fmap _ = coerce - traverse _ x = pure (coerce x) - foldMap _ _ = mempty - - These definitions of ``foldMap`` and ``traverse`` are lazier than the ones we - would otherwise derive, as they may produce results without inspecting their - arguments at all. - - See also :ref:`deriving-functor`, :ref:`deriving-foldable`, and - :ref:`deriving-traversable`. - -- Derived ``Functor``, ``Foldable``, ``Traversable``, ``Generic``, and - ``Generic1`` instances now have better, and generally better-documented, - behaviors for types with no constructors. In particular, :: - - fmap _ x = case x of - foldMap _ _ = mempty - traverse _ x = pure (case x of) - to x = case x of - to1 x = case x of - from x = case x of - from1 x = case x of - - The new behavior generally leads to more useful error messages than the - old did, and lazier semantics for ``foldMap`` and ``traverse``. - -- Derived ``Foldable`` instances now derive custom definitions for ``null`` - instead of using the default one. This leads to asymptotically better - performance for recursive types not shaped like cons-lists, and allows ``null`` - to terminate for more (but not all) infinitely large structures. - -- Derived instances for types with no constructors now have appropriate - arities: they take all their arguments before producing errors. This may not - be terribly important in practice, but it seems like the right thing to do. - Previously, we generated :: - - (==) = error ... - -Now we generate :: - - _ == _ = error ... - -- `-fsplit-sections` is now supported on x86_64 Windows and is on by default. - See :ghc-ticket:`12913`. - -- Configure on Windows now supports ``--enable-distro-toolchain`` which can be - used to build a GHC using compilers on your ``PATH`` instead of using the - bundled bindist. See :ghc-ticket:`13792` - -- The optional ``instance`` keyword is now usable in type family instance - declarations. See :ghc-ticket:`13747` - -- Lots of other bugs. See `Trac <https://ghc.haskell.org/trac/ghc/query?status=closed&milestone=8.4.1&col=id&col=summary&col=status&col=type&col=priority&col=milestone&col=component&order=priority>`_ - for a complete list. - -Runtime system -~~~~~~~~~~~~~~ - -- Function ``hs_add_root()`` was removed. It was a no-op since GHC-7.2.1 - where module initialisation stopped requiring a call to ``hs_add_root()``. - -- Proper import library support added to GHC which can handle all of the libraries produced - by dlltool. The limitation of them needing to be named with the suffix .dll.a is also removed. - See :ghc-ticket:`13606`, :ghc-ticket:`12499`, :ghc-ticket:`12498` - -- The GHCi runtime linker on Windows now supports the `big-obj` file format. - -Template Haskell -~~~~~~~~~~~~~~~~ - -``ghc`` library -~~~~~~~~~~~~~~~ - -- hsSyn Abstract Syntax Tree (AST) is now extensible via the mechanism described in `Trees that Grow <http://www.jucs.org/jucs_23_1/trees_that_grow/jucs_23_01_0042_0062_najd.pdf>`_ - - The main change for users of the GHC API is that the AST is no longer indexed - by the type used as the identifier, but by a specific index type, :: - - type GhcPs = GhcPass 'Parsed -- Old 'RdrName' type param - type GhcRn = GhcPass 'Renamed -- Old 'Name' type param - type GhcTc = GhcPass 'Typechecked -- Old 'Id' type para, - type GhcTcId = GhcTc -- Old 'TcId' type param - - The simplest way to support the current GHC as well as earlier ones is to define :: - - #if MIN_VERSION_ghc(8,3,0) - type ParseI = GhcPs - type RenameI = GhcRn - type TypecheckI = GhcTc - #else - type ParseI = RdrName - type RenameI = Name - type TypecheckI = Var - #endif - - and then replace all hardcoded index types accordingly. For polymorphic types, - the constraint :: - - #if MIN_VERSION_ghc(8,3,0) - -- |bundle up the constraints required for a trees that grow pass - type IsPass pass = (DataId pass, OutputableBndrId pass, SourceTextX pass) - else - type IsPass pass = (DataId pass, OutputableBndrId pass) - #endif - - can be used. |