Improve documentation for -fwarn-incomplete-patterns

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

diff --git a/docs/users_guide/using.xml b/docs/users_guide/using.xml
index be82322..a4c673c 100644 (file)
--- a/docs/users_guide/using.xml
+++ b/docs/users_guide/using.xml
@@ -1175,6 +1175,21 @@ foreign import "&f" f :: FunPtr t
       </varlistentry>
 
       <varlistentry>
+        <term><option>-fwarn-identities</option>:</term>
+       <listitem>
+          <indexterm><primary><option>-fwarn-identities</option></primary></indexterm>
+          <para>Causes the compiler to emit a warning when a Prelude numeric
+            conversion converts a type T to the same type T; such calls
+            are probably no-ops and can be omitted.  The functions checked for
+            are: <literal>toInteger</literal>,
+            <literal>toRational</literal>,
+            <literal>fromIntegral</literal>,
+            and <literal>realToFrac</literal>.
+          </para>
+       </listitem>
+      </varlistentry>
+
+      <varlistentry>
         <term><option>-fwarn-implicit-prelude</option>:</term>
         <listitem>
           <indexterm><primary><option>-fwarn-implicit-prelude</option></primary></indexterm>
@@ -1206,14 +1221,15 @@ foreign import "&amp;f" f :: FunPtr t
          <indexterm><primary>incomplete patterns, warning</primary></indexterm>
          <indexterm><primary>patterns, incomplete</primary></indexterm>
 
-         <para>Similarly for incomplete patterns, the function
-          <function>g</function> below will fail when applied to
+          <para>Similarly for incomplete patterns, the functions
+          <function>g</function> and <function>h</function> below will fail when applied to
           non-empty lists, so the compiler will emit a warning about
           this when <option>-fwarn-incomplete-patterns</option> is
           enabled.</para>
 
 <programlisting>
 g [] = 2
+h = \[] -> 2
 </programlisting>
 
          <para>This option isn't enabled by default because it can be