Add a --print-docdir flag

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

diff --git a/docs/users_guide/using.xml b/docs/users_guide/using.xml
index 544a6e8..9df6eb5 100644 (file)
--- a/docs/users_guide/using.xml
+++ b/docs/users_guide/using.xml
@@ -14,7 +14,7 @@
     Options can be specified in three ways:</para>
 
     <sect2>
     Options can be specified in three ways:</para>
 
     <sect2>

-      <title>command-line arguments</title>
+      <title>Command-line arguments</title>

       
       <indexterm><primary>structure, command-line</primary></indexterm>
       <indexterm><primary>command-line</primary><secondary>arguments</secondary></indexterm>
       
       <indexterm><primary>structure, command-line</primary></indexterm>
       <indexterm><primary>command-line</primary><secondary>arguments</secondary></indexterm>

@@ -26,9 +26,9 @@
 ghc [argument...]
 </screen>
 
 ghc [argument...]
 </screen>
 

-      <para>command-line arguments are either options or file names.</para>
+      <para>Command-line arguments are either options or file names.</para>

 
 

-      <para>command-line options begin with <literal>-</literal>.
+      <para>Command-line options begin with <literal>-</literal>.

       They may <emphasis>not</emphasis> be grouped:
       <option>-vO</option> is different from <option>-v -O</option>.
       Options need not precede filenames: e.g., <literal>ghc *.o -o
       They may <emphasis>not</emphasis> be grouped:
       <option>-vO</option> is different from <option>-v -O</option>.
       Options need not precede filenames: e.g., <literal>ghc *.o -o

@@ -40,7 +40,7 @@ ghc [argument...]
     </sect2>
 
     <sect2 id="source-file-options">
     </sect2>
 
     <sect2 id="source-file-options">

-      <title>command line options in source files</title>
+      <title>Command line options in source files</title>

     
       <indexterm><primary>source-file options</primary></indexterm>
 
     
       <indexterm><primary>source-file options</primary></indexterm>
 

@@ -81,7 +81,7 @@ module X where
       <para>It is not recommended to move all the contents of your
       Makefiles into your source files, but in some circumstances, the
       <literal>OPTIONS_GHC</literal> pragma is the Right Thing. (If you
       <para>It is not recommended to move all the contents of your
       Makefiles into your source files, but in some circumstances, the
       <literal>OPTIONS_GHC</literal> pragma is the Right Thing. (If you

-      use <option>-keep-hc-file-too</option> and have OPTION flags in
+      use <option>-keep-hc-file</option> and have OPTION flags in

       your module, the OPTIONS_GHC will get put into the generated .hc
       file).</para>
     </sect2>
       your module, the OPTIONS_GHC will get put into the generated .hc
       file).</para>
     </sect2>

@@ -104,8 +104,8 @@ module X where
     <indexterm><primary>mode</primary><secondary>options</secondary>
     </indexterm>
 
     <indexterm><primary>mode</primary><secondary>options</secondary>
     </indexterm>
 

-    <para>Each of GHC's command line options is classified as either
-    <firstterm>static</firstterm> or <firstterm>dynamic</firstterm> or
+    <para>Each of GHC's command line options is classified as
+    <firstterm>static</firstterm>, <firstterm>dynamic</firstterm> or

       <firstterm>mode</firstterm>:</para>
 
     <variablelist>
       <firstterm>mode</firstterm>:</para>
 
     <variablelist>

@@ -113,7 +113,7 @@ module X where
        <term>Mode flags</term>
        <listitem>
          <para>For example, <option>--make</option> or <option>-E</option>.
        <term>Mode flags</term>
        <listitem>
          <para>For example, <option>--make</option> or <option>-E</option>.

-           There may be only a single mode flag on the command line.  The
+           There may only be a single mode flag on the command line.  The

            available modes are listed in <xref linkend="modes"/>.</para>
        </listitem>
       </varlistentry>
            available modes are listed in <xref linkend="modes"/>.</para>
        </listitem>
       </varlistentry>

@@ -343,6 +343,30 @@ module X where
       <varlistentry>
        <term>
           <cmdsynopsis>
       <varlistentry>
        <term>
           <cmdsynopsis>

+            <command>ghc --supported-languages</command>
+          </cmdsynopsis>
+          <indexterm><primary><option>&ndash;&ndash;supported-languages</option></primary></indexterm>
+        </term>
+       <listitem>
+         <para>Print the supported language extensions.</para>
+       </listitem>
+      </varlistentry>
+
+      <varlistentry>
+       <term>
+          <cmdsynopsis>
+            <command>ghc --info</command>
+          </cmdsynopsis>
+          <indexterm><primary><option>&ndash;&ndash;info</option></primary></indexterm>
+        </term>
+       <listitem>
+         <para>Print information about the compiler.</para>
+       </listitem>
+      </varlistentry>
+
+      <varlistentry>
+       <term>
+          <cmdsynopsis>

             <command>ghc --version</command>
             <command>ghc -V</command>
           </cmdsynopsis>
             <command>ghc --version</command>
             <command>ghc -V</command>
           </cmdsynopsis>

@@ -379,9 +403,23 @@ module X where
          interfaces, and include files (usually something like
          <literal>/usr/local/lib/ghc-5.04</literal> on Unix).  This
          is the value of
          interfaces, and include files (usually something like
          <literal>/usr/local/lib/ghc-5.04</literal> on Unix).  This
          is the value of

-         <literal>$libdir</literal><indexterm><primary><literal>libdir</literal></primary>
-         </indexterm>in the package configuration file (see <xref
-         linkend="packages"/>).</para>
+         <literal>$libdir</literal><indexterm><primary><literal>libdir</literal></primary></indexterm>
+      in the package configuration file
+      (see <xref linkend="packages"/>).</para>
+       </listitem>
+      </varlistentry>
+
+      <varlistentry>
+       <term>
+         <cmdsynopsis>
+            <command>ghc --print-docdir</command>
+          </cmdsynopsis>
+          <indexterm><primary><option>&ndash;&ndash;print-docdir</option></primary></indexterm>
+        </term>
+       <listitem>
+         <para>Print the path to GHC's documentation directory. Note that
+      some distributions do no include the documentation, in which case
+      this directory may be empty or may not exist.</para>

        </listitem>
       </varlistentry>
 
        </listitem>
       </varlistentry>
 

@@ -394,7 +432,7 @@ module X where
       
       <para>When given the <option>&ndash;&ndash;make</option> option,
       GHC will build a multi-module Haskell program by following
       
       <para>When given the <option>&ndash;&ndash;make</option> option,
       GHC will build a multi-module Haskell program by following

-      dependencies from a single root module (usually
+      dependencies from one or more root modules (usually just

       <literal>Main</literal>).  For example, if your
       <literal>Main</literal> module is in a file called
       <filename>Main.hs</filename>, you could compile and link the
       <literal>Main</literal>).  For example, if your
       <literal>Main</literal> module is in a file called
       <filename>Main.hs</filename>, you could compile and link the

@@ -408,7 +446,7 @@ ghc &ndash;&ndash;make Main.hs
       names or module names; GHC will figure out all the modules in
       the program by following the imports from these initial modules.
       It will then attempt to compile each module which is out of
       names or module names; GHC will figure out all the modules in
       the program by following the imports from these initial modules.
       It will then attempt to compile each module which is out of

-      date, and finally if there is a <literal>Main</literal> module,
+      date, and finally, if there is a <literal>Main</literal> module,

       the program will also be linked into an executable.</para>
 
       <para>The main advantages to using <literal>ghc
       the program will also be linked into an executable.</para>
 
       <para>The main advantages to using <literal>ghc

@@ -503,7 +541,7 @@ olleh
       
       <para>The first phase to run is determined by each input-file
       suffix, and the last phase is determined by a flag.  If no
       
       <para>The first phase to run is determined by each input-file
       suffix, and the last phase is determined by a flag.  If no

-      relevant flag is present, then go all the way through linking.
+      relevant flag is present, then go all the way through to linking.

       This table summarises:</para>
       
       <informaltable>
       This table summarises:</para>
       
       <informaltable>

@@ -595,9 +633,7 @@ ghc -c Foo.hs</screen>
       
       <para>Note: The option <option>-E</option><indexterm><primary>-E
       option</primary></indexterm> runs just the pre-processing passes
       
       <para>Note: The option <option>-E</option><indexterm><primary>-E
       option</primary></indexterm> runs just the pre-processing passes

-      of the compiler, dumping the result in a file.  Note that this
-      differs from the previous behaviour of dumping the file to
-      standard output.</para>
+      of the compiler, dumping the result in a file.</para>

 
       <sect3 id="overriding-suffixes">
        <title>Overriding the default behaviour for a file</title>
 
       <sect3 id="overriding-suffixes">
        <title>Overriding the default behaviour for a file</title>

@@ -821,6 +857,7 @@ ghc -c Foo.hs</screen>
          <indexterm><primary>-W option</primary></indexterm>
          <para>Provides the standard warnings plus
          <option>-fwarn-incomplete-patterns</option>,
          <indexterm><primary>-W option</primary></indexterm>
          <para>Provides the standard warnings plus
          <option>-fwarn-incomplete-patterns</option>,

+         <option>-fwarn-dodgy-imports</option>,

          <option>-fwarn-unused-matches</option>,
          <option>-fwarn-unused-imports</option>, and
          <option>-fwarn-unused-binds</option>.</para>
          <option>-fwarn-unused-matches</option>,
          <option>-fwarn-unused-imports</option>, and
          <option>-fwarn-unused-binds</option>.</para>

@@ -828,28 +865,27 @@ ghc -c Foo.hs</screen>
       </varlistentry>
 
       <varlistentry>
       </varlistentry>
 
       <varlistentry>

-       <term><option>-w</option>:</term>
-       <listitem>
-         <indexterm><primary><option>-w</option></primary></indexterm>
-         <para>Turns off all warnings, including the standard ones.</para>
-       </listitem>
-      </varlistentry>
-
-      <varlistentry>

        <term><option>-Wall</option>:</term>
        <listitem>
          <indexterm><primary><option>-Wall</option></primary></indexterm>
          <para>Turns on all warning options that indicate potentially
          suspicious code.  The warnings that are
          <emphasis>not</emphasis> enabled by <option>-Wall</option>
        <term><option>-Wall</option>:</term>
        <listitem>
          <indexterm><primary><option>-Wall</option></primary></indexterm>
          <para>Turns on all warning options that indicate potentially
          suspicious code.  The warnings that are
          <emphasis>not</emphasis> enabled by <option>-Wall</option>

-         are:</para>
-          <itemizedlist>
-            <listitem><option>-fwarn-simple-patterns</option></listitem>
-            <listitem><option>-fwarn-tabs</option></listitem>
-            <listitem><option>-fwarn-incomplete-record-updates</option></listitem>
-            <listitem><option>-fwarn-monomorphism-restriction</option></listitem>
-            <listitem><option>-fwarn-implicit-prelude</option></listitem>
-          </itemizedlist>
+         are
+            <option>-fwarn-simple-patterns</option>,
+            <option>-fwarn-tabs</option>,
+            <option>-fwarn-incomplete-record-updates</option>,
+            <option>-fwarn-monomorphism-restriction</option>, and
+            <option>-fwarn-implicit-prelude</option>.</para>
+       </listitem>
+      </varlistentry>
+
+      <varlistentry>
+       <term><option>-w</option>:</term>
+       <listitem>
+         <indexterm><primary><option>-w</option></primary></indexterm>
+         <para>Turns off all warnings, including the standard ones and
+      those that <literal>-Wall</literal> doesn't enable.</para>

        </listitem>
       </varlistentry>
 
        </listitem>
       </varlistentry>
 

@@ -880,6 +916,20 @@ ghc -c Foo.hs</screen>
          function or type is used.  Entities can be marked as
          deprecated using a pragma, see <xref
          linkend="deprecated-pragma"/>.</para>
          function or type is used.  Entities can be marked as
          deprecated using a pragma, see <xref
          linkend="deprecated-pragma"/>.</para>

+
+         <para>This option is on by default.</para>
+       </listitem>
+      </varlistentry>
+
+      <varlistentry>
+       <term><option>-fwarn-dodgy-imports</option>:</term>
+       <listitem>
+         <indexterm><primary><option>-fwarn-dodgy-imports</option></primary>
+         </indexterm>
+         <para>Causes a warning to be emitted when a a datatype
+      <literal>T</literal> is imported
+      with all constructors, i.e. <literal>T(..)</literal>, but has been
+      exported abstractly, i.e. <literal>T</literal>.</para>

        </listitem>
       </varlistentry>
 
        </listitem>
       </varlistentry>
 

@@ -956,7 +1006,7 @@ ghc -c Foo.hs</screen>
 g [] = 2
 </programlisting>
 
 g [] = 2
 </programlisting>
 

-         <para>This option isn't enabled be default because it can be
+         <para>This option isn't enabled by default because it can be

           a bit noisy, and it doesn't always indicate a bug in the
           program.  However, it's generally considered good practice
           to cover all the cases in your functions.</para>
           a bit noisy, and it doesn't always indicate a bug in the
           program.  However, it's generally considered good practice
           to cover all the cases in your functions.</para>

@@ -984,7 +1034,7 @@ f :: Foo -> Foo
 f foo = foo { x = 6 }
 </programlisting>
 
 f foo = foo { x = 6 }
 </programlisting>
 

-         <para>This option isn't enabled be default because it can be
+         <para>This option isn't enabled by default because it can be

           very noisy, and it often doesn't indicate a bug in the
           program.</para>
        </listitem>
           very noisy, and it often doesn't indicate a bug in the
           program.</para>
        </listitem>

@@ -1057,12 +1107,8 @@ f foo = foo { x = 6 }
           inner-scope value has the same name as an outer-scope value,
           i.e. the inner value shadows the outer one.  This can catch
           typographical errors that turn into hard-to-find bugs, e.g.,
           inner-scope value has the same name as an outer-scope value,
           i.e. the inner value shadows the outer one.  This can catch
           typographical errors that turn into hard-to-find bugs, e.g.,

-          in the inadvertent cyclic definition <literal>let x = ... x
-          ... in</literal>.</para>
-
-         <para>Consequently, this option
-          <emphasis>will</emphasis> complain about cyclic recursive
-          definitions.</para>
+          in the inadvertent capture of what would be a recursive call in
+          <literal>f = ... let f = id in ... f ...</literal>.</para>

        </listitem>
       </varlistentry>
 
        </listitem>
       </varlistentry>
 

@@ -1096,7 +1142,7 @@ f foo = foo { x = 6 }
         </term>
        <listitem>
          <para>By default, the compiler will warn you if a set of
         </term>
        <listitem>
          <para>By default, the compiler will warn you if a set of

-          patterns are overlapping, i.e.,</para>
+          patterns are overlapping, e.g.,</para>

 
 <programlisting>
 f :: String -&#62; Int
 
 <programlisting>
 f :: String -&#62; Int

@@ -1121,7 +1167,7 @@ f "2"    = 2
          patterns that can fail, eg. <literal>\(x:xs)->...</literal>.
          Normally, these aren't treated as incomplete patterns by
          <option>-fwarn-incomplete-patterns</option>.</para>
          patterns that can fail, eg. <literal>\(x:xs)->...</literal>.
          Normally, these aren't treated as incomplete patterns by
          <option>-fwarn-incomplete-patterns</option>.</para>

-         <para>``Lambda-bound patterns'' includes all places where there is a single pattern,
+         <para>&ldquo;Lambda-bound patterns&rdquo; includes all places where there is a single pattern,

            including list comprehensions and do-notation.  In these cases, a pattern-match 
            failure is quite legitimate, and triggers filtering (list comprehensions) or
            the monad <literal>fail</literal> operation (monads). For example:
            including list comprehensions and do-notation.  In these cases, a pattern-match 
            failure is quite legitimate, and triggers filtering (list comprehensions) or
            the monad <literal>fail</literal> operation (monads). For example:

@@ -1131,10 +1177,6 @@ f "2"    = 2
              </programlisting>
            Switching on <option>-fwarn-simple-patterns</option> will elicit warnings about
            these probably-innocent cases, which is why the flag is off by default. </para>
              </programlisting>
            Switching on <option>-fwarn-simple-patterns</option> will elicit warnings about
            these probably-innocent cases, which is why the flag is off by default. </para>

-         <para> The <literal>deriving( Read )</literal> mechanism produces monadic code with
-           pattern matches, so you will also get misleading warnings about the compiler-generated
-           code.  (This is arguably a Bad Thing, but it's awkward to fix.)</para>
-

        </listitem>
       </varlistentry>
 
        </listitem>
       </varlistentry>
 

@@ -1159,7 +1201,7 @@ f "2"    = 2
           the Haskell defaulting mechanism for numeric types kicks
           in. This is useful information when converting code from a
           context that assumed one default into one with another,
           the Haskell defaulting mechanism for numeric types kicks
           in. This is useful information when converting code from a
           context that assumed one default into one with another,

-          e.g., the `default default' for Haskell 1.4 caused the
+          e.g., the &lsquo;default default&rsquo; for Haskell 1.4 caused the

           otherwise unconstrained value <constant>1</constant> to be
           given the type <literal>Int</literal>, whereas Haskell 98
           defaults it to <literal>Integer</literal>.  This may lead to
           otherwise unconstrained value <constant>1</constant> to be
           given the type <literal>Int</literal>, whereas Haskell 98
           defaults it to <literal>Integer</literal>.  This may lead to

@@ -1276,7 +1318,7 @@ f "2"    = 2
       <para>Note that higher optimisation levels cause more
       cross-module optimisation to be performed, which can have an
       impact on how much of your program needs to be recompiled when
       <para>Note that higher optimisation levels cause more
       cross-module optimisation to be performed, which can have an
       impact on how much of your program needs to be recompiled when

-      you change something.  This is one reaosn to stick to
+      you change something.  This is one reason to stick to

       no-optimisation when developing code.</para>
 
       <variablelist>
       no-optimisation when developing code.</para>
 
       <variablelist>

@@ -1485,6 +1527,50 @@ f "2"    = 2
 
        <varlistentry>
          <term>
 
        <varlistentry>
          <term>

+            <option>-fno-state-hack</option>
+            <indexterm><primary><option>-fno-state-hack</option></primary></indexterm>
+          </term>
+         <listitem>
+           <para>Turn off the "state hack" whereby any lambda with a
+             <literal>State#</literal> token as argument is considered to be
+             single-entry, hence it is considered OK to inline things inside
+             it.  This can improve performance of IO and ST monad code, but it
+           runs the risk of reducing sharing.</para> 
+         </listitem>
+       </varlistentry>
+
+       <varlistentry>
+         <term>
+            <option>-fomit-interface-pragmas</option>
+           <indexterm><primary><option>-fomit-interface-pragmas</option></primary></indexterm>
+          </term>
+         <listitem>
+           <para>Tells GHC to omit all inessential information from the interface file
+             generated for the module being compiled (say M).  This means that a module
+             importing M will see only the <emphasis>types</emphasis> of the functions that M exports, but not
+             their unfoldings, strictness info, etc.  Hence, for example,
+             no function exported by M will be inlined
+             into an importing module.  The benefit is that modules that import M will
+             need to be recompiled less often (only when M's exports change their type,
+             not when they change their implementation).
+             </para>
+         </listitem>
+       </varlistentry>
+
+       <varlistentry>
+         <term>
+            <option>-fignore-interface-pragmas</option>
+           <indexterm><primary><option>-fignore-interface-pragmas</option></primary></indexterm>
+          </term>
+         <listitem>
+           <para>Tells GHC to ignore all inessential information when reading interface files.
+           That is, even if <filename>M.hi</filename> contains unfolding or strictness information
+           for a function, GHC will ignore that information.</para>
+         </listitem>
+       </varlistentry>
+
+       <varlistentry>
+         <term>

             <option>-funbox-strict-fields</option>:
            <indexterm><primary><option>-funbox-strict-fields</option></primary></indexterm>
            <indexterm><primary>strict constructor fields</primary></indexterm>
             <option>-funbox-strict-fields</option>:
            <indexterm><primary><option>-funbox-strict-fields</option></primary></indexterm>
            <indexterm><primary>strict constructor fields</primary></indexterm>

@@ -1507,7 +1593,7 @@ f "2"    = 2
 
        <varlistentry>
          <term>
 
        <varlistentry>
          <term>

-            <option>-funfolding-update-in-place&lt;n&gt;</option>
+            <option>-funfolding-update-in-place=<replaceable>n</replaceable></option>

             <indexterm><primary><option>-funfolding-update-in-place</option></primary></indexterm>
           </term>
          <listitem>
             <indexterm><primary><option>-funfolding-update-in-place</option></primary></indexterm>
           </term>
          <listitem>

@@ -1525,7 +1611,7 @@ f "2"    = 2
 
        <varlistentry>
          <term>
 
        <varlistentry>
          <term>

-            <option>-funfolding-creation-threshold&lt;n&gt;</option>:
+            <option>-funfolding-creation-threshold=<replaceable>n</replaceable></option>:

            <indexterm><primary><option>-funfolding-creation-threshold</option></primary></indexterm>
            <indexterm><primary>inlining, controlling</primary></indexterm>
            <indexterm><primary>unfolding, controlling</primary></indexterm>
            <indexterm><primary><option>-funfolding-creation-threshold</option></primary></indexterm>
            <indexterm><primary>inlining, controlling</primary></indexterm>
            <indexterm><primary>unfolding, controlling</primary></indexterm>

@@ -1551,7 +1637,7 @@ f "2"    = 2
        </varlistentry>
 
        <varlistentry>
        </varlistentry>
 
        <varlistentry>

-         <term><option>-funfolding-use-threshold&lt;n&gt;</option>:</term>
+         <term><option>-funfolding-use-threshold=<replaceable>n</replaceable></option></term>

          <listitem>
            <indexterm><primary><option>-funfolding-use-threshold</option></primary></indexterm>
            <indexterm><primary>inlining, controlling</primary></indexterm>
          <listitem>
            <indexterm><primary><option>-funfolding-use-threshold</option></primary></indexterm>
            <indexterm><primary>inlining, controlling</primary></indexterm>