[project @ 2003-01-28 16:57:40 by simonmar]

[ghc-hetmet.git] / ghc / docs / users_guide / ffi-chap.sgml

diff --git a/ghc/docs/users_guide/ffi-chap.sgml b/ghc/docs/users_guide/ffi-chap.sgml
index c61e967..a92689f 100644 (file)
--- a/ghc/docs/users_guide/ffi-chap.sgml
+++ b/ghc/docs/users_guide/ffi-chap.sgml
@@ -132,64 +132,83 @@ extern HsInt foo(HsInt a0);</programlisting>
 
 <programlisting>
 #include &lt;stdio.h&gt;
-#include "foo_stub.h"
+#include "HsFFI.h"
 
-#include "RtsAPI.h"
+#ifdef __GLASGOW_HASKELL__
+#include "foo_stub.h"
+#endif
 
+#ifdef __GLASGOW_HASKELL__
 extern void __stginit_Foo ( void );
+#endif
 
 int main(int argc, char *argv[])
 {
   int i;
 
-  startupHaskell(argc, argv, __stginit_Foo);
+  hs_init(&amp;argc, &amp;argv);
+#ifdef __GLASGOW_HASKELL__
+  hs_add_root(__stginit_Foo);
+#endif
 
   for (i = 0; i < 5; i++) {
     printf("%d\n", foo(2500));
   }
 
-  shutdownHaskell();
-
+  hs_exit();
   return 0;
 }</programlisting>
 
-       <para>The call to <literal>startupHaskell()</literal>
+       <para>We've surrounded the GHC-specific bits with
+       <literal>#ifdef __GLASGOW_HASKELL__</literal>; the rest of the
+       code should be portable across Haskell implementations that
+       support the FFI standard.</para>
+
+       <para>The call to <literal>hs_init()</literal>
        initializes GHC's runtime system.  Do NOT try to invoke any
        Haskell functions before calling
-       <literal>startupHaskell()</literal>: strange things will
+       <literal>hs_init()</literal>: strange things will
        undoubtedly happen.</para>
 
        <para>We pass <literal>argc</literal> and
-       <literal>argv</literal> to <literal>startupHaskell()</literal>
+       <literal>argv</literal> to <literal>hs_init()</literal>
        so that it can separate out any arguments for the RTS
        (i.e. those arguments between
        <literal>+RTS...-RTS</literal>).</para>
 
-       <para>The third argument to <literal>startupHaskell()</literal>
-       is used for initializing the Haskell modules in the program.
-       It must be the name of the initialization function for the
-       "top" module in the program/library - in other words, the
-       module which directly or indirectly imports all the other
-       Haskell modules in the program.  In a standalone Haskell
-       program this would be module <literal>Main</literal>, but when
-       you are only using the Haskell code as a library it may not
-       be.  If your library doesn't have such a module, then it is
-       straightforward to create one, purely for this initialization
-       process.  The name of the initialization function for module
+       <para>Next, we call
+       <function>hs_add_root</function><indexterm><primary><function>hs_add_root</function></primary>
+       </indexterm>, a GHC-specific interface which is required to
+       initialise the Haskell modules in the program.  The argument
+       to <function>hs_add_root</function> should be the name of the
+       initialization function for the "root" module in your program
+       - in other words, the module which directly or indirectly
+       imports all the other Haskell modules in the program.  In a
+       standalone Haskell program the root module is normally
+       <literal>Main</literal>, but when you are using Haskell code
+       from a library it may not be.  If your program has multiple
+       root modules, then you can call
+       <function>hs_add_root</function> multiple times, one for each
+       root.  The name of the initialization function for module
        <replaceable>M</replaceable> is
        <literal>__stginit_<replaceable>M</replaceable></literal>, and
        it may be declared as an external function symbol as in the
        code above.</para>
 
        <para>After we've finished invoking our Haskell functions, we
-       can call <literal>shutdownHaskell()</literal>, which
+       can call <literal>hs_exit()</literal>, which
        terminates the RTS.  It runs any outstanding finalizers and
        generates any profiling or stats output that might have been
        requested.</para>
 
-       <para>The functions <literal>startupHaskell()</literal> and
-       <literal>shutdownHaskell()</literal> may be called only once
-       each, and only in that order.</para>
+       <para>There can be multiple calls to
+       <literal>hs_init()</literal>, but each one should be matched
+       by one (and only one) call to
+       <literal>hs_exit()</literal><footnote><para>The outermost
+       <literal>hs_exit()</literal> will actually de-initialise the
+       system.  NOTE that currently GHC's runtime cannot reliably
+       re-initialise after this has happened.</para>
+       </footnote>.</para>
 
        <para>NOTE: when linking the final program, it is normally
        easiest to do the link using GHC, although this isn't