diff options
Diffstat (limited to 'docs')
| -rw-r--r-- | docs/users_guide/flags.xml | 14 | ||||
| -rw-r--r-- | docs/users_guide/glasgow_exts.xml | 26 | ||||
| -rw-r--r-- | docs/users_guide/using.xml | 18 |
3 files changed, 43 insertions, 15 deletions
diff --git a/docs/users_guide/flags.xml b/docs/users_guide/flags.xml index 5e2e52d38d..bc583acabc 100644 --- a/docs/users_guide/flags.xml +++ b/docs/users_guide/flags.xml @@ -1061,6 +1061,12 @@ <entry><option>-XNoDeriveDataTypeable</option></entry> </row> <row> + <entry><option>-XAutoDeriveTypeable</option></entry> + <entry>Automatically derive Typeable instances for every datatype and type class declaration.</entry> + <entry>dynamic</entry> + <entry><option>-XNoAutoDeriveTypeable</option></entry> + </row> + <row> <entry><option>-XDeriveGeneric</option></entry> <entry>Enable <link linkend="deriving-typeable">deriving for the Generic class</link>.</entry> <entry>dynamic</entry> @@ -1447,6 +1453,14 @@ <entry><option>-fno-warn-warnings-deprecations</option></entry> </row> + <row> + <entry><option>-fwarn-typeable-instances</option></entry> + <entry>warn if there are any handwritten <literal>Typeable</literal> + instances (see <xref linkend="deriving-typeable"/>)</entry> + <entry>dynamic</entry> + <entry><option>-fno-warn-typeable-instances</option></entry> + </row> + </tbody> </tgroup> </informaltable> diff --git a/docs/users_guide/glasgow_exts.xml b/docs/users_guide/glasgow_exts.xml index e1d21c3506..2a0917c039 100644 --- a/docs/users_guide/glasgow_exts.xml +++ b/docs/users_guide/glasgow_exts.xml @@ -3379,19 +3379,19 @@ GHC extends this list with several more classes that may be automatically derive <literal>Typeable</literal>, and <literal>Data</literal>, defined in the library modules <literal>Data.Typeable</literal> and <literal>Data.Generics</literal> respectively. </para> -<para>An instance of <literal>Typeable</literal> can only be derived if the -data type has seven or fewer type parameters, all of kind <literal>*</literal>. -The reason for this is that the <literal>Typeable</literal> class is derived using the scheme -described in -<ulink url="http://research.microsoft.com/%7Esimonpj/papers/hmap/gmap2.ps"> -Scrap More Boilerplate: Reflection, Zips, and Generalised Casts -</ulink>. -(Section 7.4 of the paper describes the multiple <literal>Typeable</literal> classes that -are used, and only <literal>Typeable1</literal> up to -<literal>Typeable7</literal> are provided in the library.) -In other cases, there is nothing to stop the programmer writing a <literal>TypeableX</literal> -class, whose kind suits that of the data type constructor, and -then writing the data type instance by hand. +<para>Since GHC 7.8.1, <literal>Typeable</literal> is kind-polymorphic (see +<xref linkend="kind-polymorphism"/>) and can be derived for any datatype and +type class. Instances for datatypes can be derived by attaching a +<literal>deriving Typeable</literal> clause to the datatype declaration, or by +using standalone deriving (see <xref linkend="stand-alone-deriving"/>). +Instances for type classes can only be derived using standalone deriving. +Additionally, <option>-XAutoDeriveTypeable</option> will trigger the generation +of derived <literal>Typeable</literal> instances for every datatype and type +class declaration in the module it is used. +</para> +<para> +Also since GHC 7.8.1, handwritten (ie. not derived) instances of +<literal>Typeable</literal> are forbidden, and will be ignored with a warning. </para> </listitem> diff --git a/docs/users_guide/using.xml b/docs/users_guide/using.xml index 6574e9ecf3..be7e3da2ce 100644 --- a/docs/users_guide/using.xml +++ b/docs/users_guide/using.xml @@ -956,8 +956,9 @@ test.hs:(5,4)-(6,7): <option>-fwarn-missing-methods</option>, <option>-fwarn-lazy-unlifted-bindings</option>, <option>-fwarn-wrong-do-bind</option>, - <option>-fwarn-unsupported-calling-conventions</option>, and - <option>-fwarn-dodgy-foreign-imports</option>. The following + <option>-fwarn-unsupported-calling-conventions</option>, + <option>-fwarn-dodgy-foreign-imports</option>, and + <option>-fwarn-typeable-instances</option>. The following flags are simple ways to select standard “packages” of warnings: </para> @@ -1682,6 +1683,19 @@ f "2" = 2 </listitem> </varlistentry> + <varlistentry> + <term><option>-fwarn-typeable-instances</option>:</term> + <listitem> + <indexterm><primary><option>-fwarn-typeable-instances</option></primary></indexterm> + <indexterm><primary>typeable instances, warning</primary></indexterm> + + <para>Report handwritten (ie. not derived) instances of the + <literal>Typeable</literal> class. These are ignore by the compiler; + only derived instances of <literal>Typeable</literal> are allowed. + </para> + </listitem> + </varlistentry> + </variablelist> <para>If you're feeling really paranoid, the |