users_guide: note -XPatternSynonyms is required for use sites
authorAustin Seipp <austin@well-typed.com>
Mon, 7 Apr 2014 15:15:05 +0000 (10:15 -0500)
committerAustin Seipp <austin@well-typed.com>
Mon, 7 Apr 2014 16:07:41 +0000 (11:07 -0500)
Signed-off-by: Austin Seipp <austin@well-typed.com>
docs/users_guide/glasgow_exts.xml

index 44f0d98..c5ecbe3 100644 (file)
@@ -856,9 +856,11 @@ y)</literal> will not be coalesced.
 </title>
 
 <para>
-Pattern synonyms are enabled by the flag <literal>-XPatternSynonyms</literal>.
-More information and examples of view patterns can be found on the
-<ulink url="http://ghc.haskell.org/trac/ghc/wiki/PatternSynonyms">Wiki
+Pattern synonyms are enabled by the flag
+<literal>-XPatternSynonyms</literal>, which is required for both
+defining them <emphasis>and</emphasis> using them.  More information
+and examples of view patterns can be found on the <ulink
+url="http://ghc.haskell.org/trac/ghc/wiki/PatternSynonyms">Wiki
 page</ulink>.
 </para>