Mention that generalised list comprehensions are enabled with -XTransformListComp

[ghc-hetmet.git] / docs / users_guide / glasgow_exts.xml

diff --git a/docs/users_guide/glasgow_exts.xml b/docs/users_guide/glasgow_exts.xml
index 3120601..a08ace9 100644 (file)
--- a/docs/users_guide/glasgow_exts.xml
+++ b/docs/users_guide/glasgow_exts.xml
@@ -1008,6 +1008,7 @@ This name is not supported by GHC.
        paper <ulink url="http://research.microsoft.com/~simonpj/papers/list-comp">
          Comprehensive comprehensions: comprehensions with "order by" and "group by"</ulink>,
     except that the syntax we use differs slightly from the paper.</para>
+<para>The extension is enabled with the flag <option>-XTransformListComp</option>.</para>
 <para>Here is an example: 
 <programlisting>
 employees = [ ("Simon", "MS", 80)
@@ -2353,6 +2354,16 @@ otherwise is a <emphasis>generalised</emphasis> data type (<xref linkend="gadt"/
 </para></listitem>
 
 <listitem><para>
+As with other type signatures, you can give a single signature for several data constructors.
+In this example we give a single signature for <literal>T1</literal> and <literal>T2</literal>:
+<programlisting>
+  data T a where
+    T1,T2 :: a -> T a
+    T3 :: T a
+</programlisting>
+</para></listitem>
+
+<listitem><para>
 The type signature of
 each constructor is independent, and is implicitly universally quantified as usual. 
 Different constructors may have different universally-quantified type variables
@@ -5853,6 +5864,8 @@ Wiki page</ulink>.
                  <itemizedlist>
                    <listitem><para> an expression; the spliced expression must
                    have type <literal>Q Exp</literal></para></listitem>
+                   <listitem><para> an type; the spliced expression must
+                   have type <literal>Q Typ</literal></para></listitem>
                    <listitem><para> a list of top-level declarations; the spliced expression must have type <literal>Q [Dec]</literal></para></listitem>
                    </itemizedlist>
                </para>
@@ -5901,7 +5914,7 @@ Wiki page</ulink>.
 (Compared to the original paper, there are many differences of detail.
 The syntax for a declaration splice uses "<literal>$</literal>" not "<literal>splice</literal>".
 The type of the enclosed expression must be  <literal>Q [Dec]</literal>, not  <literal>[Q Dec]</literal>.
-Type splices are not implemented, and neither are pattern splices or quotations.
+Pattern splices and quotations are not implemented.)
 
 </sect2>