Repository : ssh://darcs.haskell.org//srv/darcs/ghc On branch : master
http://hackage.haskell.org/trac/ghc/changeset/b65562c7000ca745fae7ad1a6fd546951abdd14a >--------------------------------------------------------------- commit b65562c7000ca745fae7ad1a6fd546951abdd14a Author: Jose Pedro Magalhaes <[email protected]> Date: Tue Jun 26 15:07:20 2012 +0100 Mention Generic1 in the user's guide >--------------------------------------------------------------- docs/users_guide/glasgow_exts.xml | 39 +++++++++++++++++++++--------------- 1 files changed, 23 insertions(+), 16 deletions(-) diff --git a/docs/users_guide/glasgow_exts.xml b/docs/users_guide/glasgow_exts.xml index c941df1..df1ff2c 100644 --- a/docs/users_guide/glasgow_exts.xml +++ b/docs/users_guide/glasgow_exts.xml @@ -3339,8 +3339,9 @@ then writing the data type instance by hand. </listitem> <listitem><para> With <option>-XDeriveGeneric</option>, you can derive -instances of the class <literal>Generic</literal>, defined in -<literal>GHC.Generics</literal>. You can use these to define generic functions, +instances of the classes <literal>Generic</literal> and +<literal>Generic1</literal>, defined in <literal>GHC.Generics</literal>. +You can use these to define generic functions, as described in <xref linkend="generic-programming"/>. </para></listitem> @@ -9884,8 +9885,9 @@ data (:*:) f g p = f p :*: g p </para> <para> -The <literal>Generic</literal> class mediates between user-defined datatypes -and their internal representation as a sum-of-products: +The <literal>Generic</literal> and <literal>Generic1</literal> classes mediate +between user-defined datatypes and their internal representation as a +sum-of-products: <programlisting> class Generic a where @@ -9895,9 +9897,17 @@ class Generic a where from :: a -> (Rep a) x -- Convert from the representation to the datatype to :: (Rep a) x -> a + +class Generic1 f where + type Rep1 f :: * -> * + + from1 :: f a -> Rep1 f a + to1 :: Rep1 f a -> f a </programlisting> -Instances of this class can be derived by GHC with the +<literal>Generic1</literal> is used for functions that can only be defined over +type containers, such as <literal>map</literal>. +Instances of these classes can be derived by GHC with the <option>-XDeriveGeneric</option> (<xref linkend="deriving-typeable"/>), and are necessary to be able to define generic instances automatically. </para> @@ -9912,7 +9922,7 @@ instance Generic (UserTree a) where type Rep (UserTree a) = M1 D D1UserTree ( M1 C C1_0UserTree ( - M1 S NoSelector (K1 P a) + M1 S NoSelector (K1 R a) :*: M1 S NoSelector (K1 R (UserTree a)) :*: M1 S NoSelector (K1 R (UserTree a))) :+: M1 C C1_1UserTree U1) @@ -10007,17 +10017,20 @@ instance (Serialize a) => Serialize (UserTree a) The default method for <literal>put</literal> is then used, corresponding to the generic implementation of serialization. + +For more examples of generic functions please refer to the +<ulink url="http://hackage.haskell.org/package/generic-deriving";>generic-deriving</ulink> +package on Hackage. </para> </sect2> - <sect2> <title>More information</title> <para> -For more detail please refer to the -<ulink url="http://www.haskell.org/haskellwiki/Generics";>HaskellWiki page</ulink> -or the original paper: +For more details please refer to the +<ulink url="http://www.haskell.org/haskellwiki/GHC.Generics";>HaskellWiki +page</ulink> or the original paper: </para> <itemizedlist> @@ -10032,12 +10045,6 @@ Jose Pedro Magalhaes, Atze Dijkstra, Johan Jeuring, and Andres Loeh. </listitem> </itemizedlist> -<emphasis>Note</emphasis>: the current support for generic programming in GHC -is preliminary. In particular, we only allow deriving instances for the -<literal>Generic</literal> class. Support for deriving -<literal>Generic1</literal> (and thus enabling generic functions of kind -<literal>* -> *</literal> such as <literal>fmap</literal>) will come at a -later stage. </sect2> </sect1> _______________________________________________ Cvs-ghc mailing list [email protected] http://www.haskell.org/mailman/listinfo/cvs-ghc
