<title>Options related to a particular phase</title>
<sect2 id="replacing-phases">
- <title>Replacing the program for one or more phases.</title>
+ <title>Replacing the program for one or more phases</title>
<indexterm><primary>phases, changing</primary></indexterm>
<para>You may specify that a different program be used for one
the <Command>ghc</Command> has wired into it. For example, you
might want to try a different assembler. The following options
allow you to change the external program used for a given
- compilation phases:</para>
+ compilation phase:</para>
+
+ <variablelist>
+ <varlistentry>
+ <term><option>-pgmL</option> <replaceable>cmd</replaceable></term>
+ <indexterm><primary><option>-pgmL</option></primary>
+ </indexterm>
+ <listitem>
+ <para>Use <replaceable>cmd</replaceable> as the literate
+ pre-processor.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><option>-pgmP</option> <replaceable>cmd</replaceable></term>
+ <indexterm><primary><option>-pgmP</option></primary>
+ </indexterm>
+ <listitem>
+ <para>Use <replaceable>cmd</replaceable> as the C
+ pre-processor (with <option>-cpp</option> only).</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><option>-pgmc</option> <replaceable>cmd</replaceable></term>
+ <indexterm><primary><option>-pgmc</option></primary>
+ </indexterm>
+ <listitem>
+ <para>Use <replaceable>cmd</replaceable> as the C
+ compiler.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><option>-pgma</option> <replaceable>cmd</replaceable></term>
+ <indexterm><primary><option>-pgma</option></primary>
+ </indexterm>
+ <listitem>
+ <para>Use <replaceable>cmd</replaceable> as the
+ assembler.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><option>-pgml</option> <replaceable>cmd</replaceable></term>
+ <indexterm><primary><option>-pgml</option></primary>
+ </indexterm>
+ <listitem>
+ <para>Use <replaceable>cmd</replaceable> as the
+ linker.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><option>-pgmdll</option> <replaceable>cmd</replaceable></term>
+ <indexterm><primary><option>-pgmdll</option></primary>
+ </indexterm>
+ <listitem>
+ <para>Use <replaceable>cmd</replaceable> as the DLL
+ generator.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><option>-pgmdep</option> <replaceable>cmd</replaceable></term>
+ <indexterm><primary><option>-pgmdep</option></primary>
+ </indexterm>
+ <listitem>
+ <para>Use <replaceable>cmd</replaceable> as the dependency
+ generator.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><option>-pgmF</option> <replaceable>cmd</replaceable></term>
+ <indexterm><primary><option>-pgmF</option></primary>
+ </indexterm>
+ <listitem>
+ <para>Use <replaceable>cmd</replaceable> as the
+ pre-processor (with <option>-F</option> only).</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
</sect2>
<sect2 id="forcing-options-through">
- <title>Forcing options to a particular phase.</title>
+ <title>Forcing options to a particular phase</title>
<indexterm><primary>forcing GHC-phase options</primary></indexterm>
<para>Options can be forced through to a particlar compilation
</varlistentry>
</variablelist>
- <para>A small word of warning: <option>-cpp</option> is not
- friendly to “string gaps”.<indexterm><primary>-cpp
- vs string gaps</primary></indexterm><indexterm><primary>string
- gaps vs -cpp</primary></indexterm>. In other words, strings
- such as the following:</para>
+ <sect3 id="cpp-string-gaps">
+ <title>CPP and string gaps</title>
+
+ <para>A small word of warning: <option>-cpp</option> is not
+ friendly to “string gaps”.<indexterm><primary>-cpp
+ vs string gaps</primary></indexterm><indexterm><primary>string
+ gaps vs -cpp</primary></indexterm>. In other words, strings
+ such as the following:</para>
<ProgramListing>
strmod = "\
\ p \
\ "
</ProgramListing>
+
+ <para>don't work with <option>-cpp</option>;
+ <filename>/usr/bin/cpp</filename> elides the backslash-newline
+ pairs.</para>
+
+ <para>However, it appears that if you add a space at the end
+ of the line, then <command>cpp</command> (at least GNU
+ <command>cpp</command> and possibly other
+ <command>cpp</command>s) leaves the backslash-space pairs
+ alone and the string gap works as expected.</para>
+ </sect3>
+ </sect2>
- <para>don't work with <option>-cpp</option>;
- <filename>/usr/bin/cpp</filename> elides the backslash-newline
- pairs.</para>
+ <sect2 id="pre-processor">
+ <title>Options affecting a Haskell pre-processor</title>
+
+ <indexterm><primary>pre-processing: custom</primary></indexterm>
+ <indexterm><primary>Pre-processor options</primary></indexterm>
- <para>However, it appears that if you add a space at the end of
- the line, then <command>cpp</command> (at least GNU
- <command>cpp</command> and possibly other
- <command>cpp</command>s) leaves the backslash-space pairs alone
- and the string gap works as expected.</para>
+ <variablelist>
+ <varlistentry>
+ <term><option>-F</option></term>
+ <indexterm><primary><option>-F</option></primary></indexterm>
+ <listitem>
+ <para>A custom pre-processor is run over your Haskell
+ source file only if the <option>-F</option> option
+ <indexterm><primary>-F</primary></indexterm> is given.
+ </para>
+ <para>
+ Running a custom pre-processor at compile-time is in some
+ settings appropriate and useful. The <option>-F</option>
+ option lets you run a pre-processor as part of the overall
+ GHC compilation pipeline, which has the advantage over
+ running a Haskell pre-processor separately in that it
+ works in interpreted mode and you can continue to take
+ reap the benefits of GHC's recompilation checker.
+ </para>
+ <para>
+ The pre-processor is run just before the Haskell
+ compiler proper processes the Haskell input, but after
+ the literate markup has been stripped away and (possibly)
+ the C pre-processor has washed the Haskell input.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><option>-pgmF</option> <replaceable>cmd</replaceable></term>
+ <indexterm><primary><option>-pgmF</option> <replaceable>cmd</replaceable></primary></indexterm>
+ <listitem>
+ <para>Use <replaceable>cmd</replaceable> as the Haskell
+ pre-processor. When invoked, the
+ <replaceable>cmd</replaceable> pre-processor is given at
+ least three arguments on its command-line: the first
+ argument is the name of the original source file, the second
+ is the name of the file holding the input, and the third is
+ the name of the file where
+ <replaceable>cmd</replaceable> should write its output to.
+ </para>
+ <para>Additional arguments to the
+ <replaceable>cmd</replaceable> pre-processor can be passed
+ in using the <option>-optF</option> option. These are fed to
+ <replaceable>cmd</replaceable> on the command line after the
+ three standard input and output arguments.
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
</sect2>
<sect2 id="options-C-compiler">
code generator.</para>
</listitem>
</varlistentry>
+
+ <varlistentry>
+ <term><option>-fno-code</option></term>
+ <indexterm><primary><option>-fno-code</option></primary>
+ </indexterm>
+ <listitem>
+ <para>Omit code generation (and all later phases)
+ altogether. Might be of some use if you just want to see
+ dumps of the intermediate compilation phases.</para>
+ </listitem>
+ </varlistentry>
</variablelist>
</sect2>
come <emphasis>before</emphasis>
<option>-l</option><replaceable>bar</replaceable> on the
command line.</para>
+
+ <para>There's one other gotcha to bear in mind when using
+ external libraries: if the library contains a
+ <literal>main()</literal> function, then this will be
+ linked in preference to GHC's own
+ <literal>main()</literal> function
+ (eg. <literal>libf2c</literal> and <literal>libl</literal>
+ have their own <literal>main()</literal>s). This is
+ because GHC's <literal>main()</literal> comes from the
+ <literal>HSrts</literal> library, which is normally
+ included <emphasis>after</emphasis> all the other
+ libraries on the linker's command line. To force GHC's
+ <literal>main()</literal> to be used in preference to any
+ other <literal>main()</literal>s from external libraries,
+ just add the option <option>-lHSrts</option> before any
+ other libraries on the command line.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><option>-no-link</option></term>
+ <indexterm>
+ <primary><option>-no-link</option></primary>
+ </indexterm>
+ <listitem>
+ <para>Omit the link step. This flag can be useful if you
+ want to avoid linking in <option>--make</option> mode,
+ where linking is normally done automatically if the program
+ contains a <literal>Main</literal> module.</para>
</listitem>
</varlistentry>
</varlistentry>
<varlistentry>
+ <term><option>-framework</option> <replaceable>name</replaceable></term>
+ <indexterm><primary><option>-framework</option></primary></indexterm>
+ <listitem>
+ <para>On Darwin/MacOS X only, link in the framework <replaceable>name</replaceable>.
+ This option corresponds to the <option>-framework</option> option for Apple's Linker.
+ Please note that frameworks and packages are two different things - frameworks don't
+ contain any haskell code. Rather, they are Apple's way of packaging shared libraries.
+ To link to Apple's “Carbon” API, for example, you'd use
+ <option>-framework Carbon</option>.
+ </para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
<term><option>-L</option><replaceable>dir</replaceable></term>
<indexterm><primary><option>-L</option></primary></indexterm>
<listitem>
</varlistentry>
<varlistentry>
+ <term><option>-framework-path</option><replaceable>dir</replaceable></term>
+ <indexterm><primary><option>-framework-path</option></primary></indexterm>
+ <listitem>
+ <para>On Darwin/MacOS X only, prepend the directory <replaceable>dir</replaceable> to
+ the framework directories path. This option corresponds to the <option>-F</option>
+ option for Apple's Linker (<option>-F</option> already means something else for GHC).</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
<term><option>-split-objs</option></term>
<indexterm><primary><option>-split-objs</option></primary></indexterm>
<listitem>
</varlistentry>
<varlistentry>
+ <term><option>-main-is <replaceable>thing</replaceable></option></term>
+ <indexterm><primary><option>-main-is</option></primary></indexterm>
+ <indexterm><primary>specifying your own main function</primary></indexterm>
+ <listitem>
+ <para> The normal rule in Haskell is that your program must supply a <literal>main</literal>
+ function in module <literal>Main</literal>. When testing, it is often convenient
+ to change which function is the "main" one, and the <option>-main-is</option> flag
+ allows you to do so. The <replaceable>thing</replaceable> can be one of:
+ <itemizedlist>
+ <listitem><para>A lower-case identifier <literal>foo</literal>. GHC assumes that the main function is <literal>Main.foo</literal>.</para></listitem>
+ <listitem><para>An module name <literal>A</literal>. GHC assumes that the main function is <literal>A.main</literal>.</para></listitem>
+ <listitem><para>An qualified name <literal>A.foo</literal>. GHC assumes that the main function is <literal>A.foo</literal>.</para></listitem>
+ </itemizedlist>
+ Strictly speaking, <option>-main-is</option> is not a link-phase flag at all; it has no effect on the link step.
+ The flag must be specified when compiling the module containing the specified main function (e.g. module <literal>A</literal>
+ in the latter two items above. It has no effect for other modules (and hence can safely be given to <literal>ghc --make</literal>).
+ </para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
<term><option>-no-hs-main</option></term>
<indexterm><primary><option>-no-hs-main</option></primary></indexterm>
<indexterm><primary>linking Haskell libraries with foreign code</primary></indexterm>
as part of another (non-Haskell) program, the RTS will not
be supplying its definition of <function>main()</function>
at link-time, you will have to. To signal that to the
- driver script when linking, use
- <option>-no-hs-main</option>.</para>
+ compiler when linking, use
+ <option>-no-hs-main</option>. See also <xref linkend="using-own-main">.</para>
<para>Notice that since the command-line passed to the
linker is rather involved, you probably want to use
though, just try linking once with <option>-v</option> on
to see what options the driver passes through to the
linker.</para>
+
+ <para>The <option>-no-hs-main</option> flag can also be
+ used to persuade the compiler to do the link step in
+ <option>--make</option> mode when there is no Haskell
+ <literal>Main</literal> module present (normally the
+ compiler will not attempt linking when there is no
+ <literal>Main</literal>).</para>
</listitem>
</varlistentry>
</variablelist>
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