path: root/ghc/docs/users_guide/6.0-notes.xml

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<sect1 id="release-6-0">
  <title>Release notes for version 6.0</title>

  <sect2>
    <title>User-visible compiler changes</title>
    <itemizedlist>
      <listitem>
	<para>Template Haskell, a new feature for compile-time
	metaprogramming has been introduced.  See <xref
	linkend="template-haskell"/>.</para>
      </listitem>
      <listitem>
	<para>INLINE pragmas on methods in class or instance
	declarations now work properly.</para>
      </listitem>
      <listitem>
	<para>Recursive do-notation (aka <literal>mdo</literal>) is
	now supported.  See <xref linkend="mdo-notation"/>.</para>
      </listitem>
      <listitem>
	<para>There is now a native code generator for PowerPC
	platforms.</para>
      </listitem>
      <listitem>
	<para>Profiling: the <option>-xt</option> RTS option enables
	inclusion of thread stacks in a heap profile.  See <xref
	linkend="rts-options-heap-prof"/>.</para>
      </listitem>
      <listitem>
	<para>Non-blocking I/O is now supported on Windows.</para>
      </listitem>
      <listitem>
	<para>The <ulink url="../libraries/base/Data.Dynamic.html#Typeable"><literal>Typeable</literal></ulink> class can now be
	derived, and the implementation of <literal>Typeable</literal>
	is now more efficient.</para>
      </listitem>
    </itemizedlist>
  </sect2>
  
  <sect2>
    <title>User-visible interpreter (GHCi) changes</title>
    <itemizedlist>
      <listitem>
	<para>Loading a <literal>Main</literal> module that does not
	define <literal>main</literal> is no longer an error, although
	GHCi will still emit a warning in this case.</para>
      </listitem>
    </itemizedlist>
  </sect2>

  <sect2>
    <title>User-visible library changes</title>
    <itemizedlist>
      <listitem>
	<para>Hierarchical libraries are now available without needing
	to specify an explicit <option>-package</option> flag.  There
	are some exceptions to this rule (see <xref
	linkend="using-packages"/>), but if you stick to GHCi and
	<option>--make</option> mode then there will normally be no
	need to specify <option>-package</option> options at
	all.</para>

	<para>Non-hierarchical libraries
	(i.e. <literal>hslibs</literal> libraries) still need to be
	explicitly requested with <option>-package</option>
	options.</para>
      </listitem>

      <listitem>
	<para>The <literal>Posix</literal> library has been rewritten.
	It is now a hierarchical library rooted at
	<literal>System.Posix</literal>, and has some additions aimed
	at supporting the latest revision of the POSIX standard (IEEE
	Std 1003.1-2001).  See the <ulink
	url="../libraries/unix/index.html"><literal>unix</literal>
	package</ulink> for details.</para>

	<para>The old <literal>posix</literal> package is still
	available for backwards compatibility, but is deprecated and
	will be removed in a future release.</para>
      </listitem>

      <listitem>
	<para><ulink url="../libraries/base/Data.IORef.html"><literal>Data.IORef</literal></ulink>: Added <literal>atomicModifyIORef</literal>.</para>
      </listitem>

      <listitem>
	<para><ulink url="../libraries/base/System.Cmd.html"><literal>System.Cmd</literal></ulink>: Added <literal>rawSystem</literal>.</para>
      </listitem>

      <listitem>
	<para><ulink
	url="../libraries/base/System.Environment.html"><literal>System.Environment</literal></ulink>:
	Added <literal>withArgs</literal> and <literal>withProgName</literal>.</para>
      </listitem>

      <listitem>
	<para><ulink
	url="../libraries/network/Network.Socket.html"><literal>Network.Socket</literal></ulink>:
	Added <literal>sendFd</literal> and <literal>recvFd</literal>.</para>
      </listitem>

      <listitem>
	<para>The <literal>Readline</literal> library has moved to
	<ulink
	url="../libraries/readline/System.Console.Readline.html"><literal>System.Console.Readline</literal></ulink>,
	and is in a package of its own
	(<literal>readline</literal>).</para>
      </listitem>

      <listitem>
	<para>The non-hierarchical versions of the FFI libraries are
	now all available without needing to specify <literal>-package
	lang</literal> (they are actually now in the
	<literal>haskell98</literal> package, which is available by
	default).</para>
      </listitem>

      <listitem>
	<para><ulink
	url="../libraries/network/Network.BSD.html"><literal>Network.BSD</literal></ulink>:
	<literal>symlink</literal> and <literal>readline</literal> are
	now deprecated; use
	<literal>System.Posix.createSymbolicLink</literal> and
	<literal>System.Posix.readSymbolicLink</literal>
	respectively.</para>
      </listitem>

      <listitem>
	<para><ulink
	url="../libraries/base/Control.Exception.html"><literal>Control.Exception</literal></ulink>:
	Added <literal>mapException</literal>.</para>
      </listitem>

      <listitem>
	<para><ulink
	url="../libraries/base/Data.Dynamic.html"><literal>Data.Dynamic</literal></ulink>:
	various changes to make the implementation of
	<literal>Typeable</literal> more efficient.  This entails some
	changes to the interface, and affects how instances of
	<literal>Typeable</literal> are defined.</para>
      </listitem>

      <listitem>
	<para><ulink
	url="../libraries/base/Data.Tree.html"><literal>Data.Tree</literal></ulink>
	is a new library for trees.</para>
      </listitem>

      <listitem>
	<para><ulink
	url="../libraries/base/Data.Graph.html"><literal>Data.Graph</literal></ulink>
	is a new library for graphs.</para>
      </listitem>

      <listitem>
	<para><ulink
	url="../libraries/base/System.IO.html"><literal>System.IO</literal></ulink>:
	Removed <literal>bracket</literal> and
	<literal>bracket_</literal> (use the versions from
	<literal>Control.Exception</literal> instead).</para>
      </listitem>

      <listitem>
	<para><ulink
	url="../libraries/base/System.IO.html"><literal>System.IO</literal></ulink>:
	The <literal>IOError</literal> type is now a synonym for
	<literal>IOException</literal>, whereas previously it was a
	synonym for <literal>Exception</literal>.  This has various
	consequences, one of which is that the types of
	<literal>System.IO.catch</literal> and
	<literal>Control.Exception.catch</literal> are now different
	(useful, because they do different things).</para>
      </listitem>

      <listitem>
	<para><ulink
	url="../libraries/base/System.IO.Error.html"><literal>System.IO.Error</literal></ulink>:
	added <literal>annotateIOError</literal>,
	<literal>modifyIOError</literal>, and <literal>ioeSet{ErrorType,ErrorString,Handle,FileName}</literal>.</para>
      </listitem>

      <listitem>
	<para><ulink
	url="../libraries/base/Text.ParserCombinators.ReadP.html"><literal>Text.ParserCombinators.ReadP</literal></ulink>:
	lots of updates.</para>
      </listitem>

      <listitem>
	<para><literal>Control.Monad.Monoid</literal> is now <ulink url="../libraries/base/Data.Monoid.html"><literal>Data.Monoid</literal></ulink>.</para>
      </listitem>

      <listitem>
	<para><ulink
	url="../libraries/base/Data.PackedString.html"><literal>Data.PackedString</literal></ulink>:
	added <literal>joinPS</literal>, <literal>unwordsPS</literal>
	and <literal>unlinesPS</literal>.</para>
      </listitem>

      <listitem>
	<para><ulink
	url="../libraries/base/Data.HashTable.html"><literal>Data.HashTable</literal></ulink>
	is a new dynamic hash-table implementation.</para>
      </listitem>

      <listitem>
	<para>Added <ulink
	url="../libraries/unix/System.Sendfile.html"><literal>System.Sendfile</literal></ulink>.</para>
      </listitem>

      <listitem>
	<para>Added <ulink
	url="../libraries/base/Foreign.Marshal.Pool.html"><literal>Foreign.Marshal.Pool</literal></ulink>.</para>
      </listitem>

      <listitem>
	<para><ulink
	url="../libraries/base/Data.Bits.html"><literal>Data.Bits</literal></ulink>:
	<literal>shiftL</literal>, <literal>shiftR</literal>,
	<literal>rotateL</literal>, and <literal>rotateR</literal> are
	now methods of the <literal>Bite</literal> class.</para>
      </listitem>

      <listitem>
	<para>The FFI libraries now conform to the latest version of
	the FFI spec:</para>
	<itemizedlist>
	  <listitem>
	    <para>Added <ulink
	    url="../libraries/base/Foreign.ForeignPtr.html#mallocForeignPtr"><literal>Foreign.ForeignPtr.mallocForeignPtr</literal></ulink>
	    and friends.</para>
	  </listitem>
	  <listitem>
	    <para>Finalizers added to a <literal>ForeignPtr</literal>
	    with <literal>addForeignPtrFinalizer</literal> are now run
	    in strict order; namely the reverse of the order they were
	    added.</para>
	  </listitem>
	  <listitem>
	    <para><literal>Foreign.C.TypesISO</literal> has been
	    merged into <ulink
	    url="../libraries/base/Foreign.C.Types.html"><literal>Foreign.C.Types</literal></ulink>.</para>
	  </listitem>
	</itemizedlist>
      </listitem>
    </itemizedlist>
  </sect2>

  <sect2>
    <title>Experimental features</title>
    <itemizedlist>
      <listitem>
	<para>The <literal>Data</literal> class provides for generic
	data traversals and folds; see <ulink
	url="../libraries/base/Data.Generics.html"><literal>Data.Generics</literal></ulink>.
	<literal>Data</literal> can be derived for arbitrary
	datatypes.  The <literal>Data</literal> class is still
	experimental, so its contents may change in the future.</para>
      </listitem>
      <listitem>
	<para>Several bugs have been fixed in the threaded RTS, and it
	should now be rather more robust (it should still be
	considered experimental, however).</para>
      </listitem>
    </itemizedlist>
  </sect2>

  <sect2>
    <title>Internal changes</title>
    <itemizedlist>
      <listitem>
	<para>Sweeping changes to the compiler and runtime system to
	change the evaluation model from <quote>push/enter</quote> to
	<quote>eval/apply</quote>.  The bottom line is that the
	compiler is now more portable and some of the complexity is
	now more centralised, while performance and binary sizes
	remain about the same.</para>
	
	<para>A paper describing these changes can be found <ulink
	url="http://research.microsoft.com/~simonpj/papers/eval-apply">here</ulink>.</para>
      </listitem>
      <listitem>
	<para>The test suite is now driven by a Python script and is
	rather more flexible and robust.  It now supports building
	tests several different "ways", and as a result we now run
	each test with optimisation, profiling, native code
	generation, and GHCi in addition to the vanilla way.</para>
      </listitem>
      <listitem>
	<para>The build system now supports bootstrapping the compiler
	in a single build tree.  By default, typing
	<literal>make</literal> at the top level will bootstrap the
	compiler once to create a stage-2 compiler.  See the Building
	Guide for more details.</para>
      </listitem>
      <listitem>
	<para>The RTS debugging flags are no longer represented by a
	bitfield and now have single-character names.  For example, to
	turn on scheduler debugging output, use <literal>-Ds</literal>
	rather than <literal>-D1</literal>.</para>
      </listitem>
      <listitem>
	<para>The compiler no longer requires any packages from
	<literal>hslibs</literal> to bootstrap.  It is enough to
	compile <literal>fptools/libraries</literal> before building
	the stage 2 compiler.</para>
      </listitem>
    </itemizedlist>
  </sect2>

</sect1>

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