<entry><option>-XNoGADTs</option></entry>
</row>
<row>
+ <entry><option>-XGADTSyntax</option></entry>
+ <entry>Enable <link linkend="gadt-style">generalised algebraic data type syntax</link>.
+ </entry>
+ <entry>dynamic</entry>
+ <entry><option>-XNoGADTSyntax</option></entry>
+ </row>
+ <row>
<entry><option>-XTypeFamilies</option></entry>
<entry>Enable <link linkend="type-families">type families</link>.</entry>
<entry>dynamic</entry>
<sect2 id="gadt-style">
<title>Declaring data types with explicit constructor signatures</title>
-<para>GHC allows you to declare an algebraic data type by
+<para>When the <literal>GADTSyntax</literal> extension is enabled,
+GHC allows you to declare an algebraic data type by
giving the type signatures of constructors explicitly. For example:
<programlisting>
data Maybe a where