Get rid of callouts since Markdown doesn't support them

doc/manual/expressions/expression-syntax.xml

@@ -6,33 +6,31 @@
 
 <title>Expression Syntax</title>
 
-<example xml:id='ex-hello-nix'><title>Nix expression for GNU Hello
-(<filename>default.nix</filename>)</title>
-<programlisting>
-{ stdenv, fetchurl, perl }: <co xml:id='ex-hello-nix-co-1' />
+<para>Here is a Nix expression for GNU Hello:</para>
 
-stdenv.mkDerivation { <co xml:id='ex-hello-nix-co-2' />
-  name = "hello-2.1.1"; <co xml:id='ex-hello-nix-co-3' />
-  builder = ./builder.sh; <co xml:id='ex-hello-nix-co-4' />
-  src = fetchurl { <co xml:id='ex-hello-nix-co-5' />
+<programlisting>
+{ stdenv, fetchurl, perl }: ①
+
+stdenv.mkDerivation { ②
+  name = "hello-2.1.1"; ③
+  builder = ./builder.sh; ④
+  src = fetchurl { ⑤
     url = "ftp://ftp.nluug.nl/pub/gnu/hello/hello-2.1.1.tar.gz";
     sha256 = "1md7jsfd8pa45z73bz1kszpp01yw6x5ljkjk2hx7wl800any6465";
   };
-  inherit perl; <co xml:id='ex-hello-nix-co-6' />
+  inherit perl; ⑥
 }</programlisting>
-</example>
 
-<para><xref linkend='ex-hello-nix' /> shows a Nix expression for GNU
-Hello.  It's actually already in the Nix Packages collection in
+<para>This file is actually already in the Nix Packages collection in
 <filename>pkgs/applications/misc/hello/ex-1/default.nix</filename>.
 It is customary to place each package in a separate directory and call
 the single Nix expression in that directory
 <filename>default.nix</filename>.  The file has the following elements
 (referenced from the figure by number):
 
-<calloutlist>
+<orderedlist>
 
-  <callout arearefs='ex-hello-nix-co-1'>
+  <listitem>
 
     <para>This states that the expression is a
     <emphasis>function</emphasis> that expects to be called with three
@@ -57,9 +55,9 @@ the single Nix expression in that directory
     function; when given the required arguments, the body should
     describe how to build an instance of the Hello package.</para>
 
-  </callout>
+  </listitem>
 
-  <callout arearefs='ex-hello-nix-co-2'>
+  <listitem>
 
     <para>So we have to build a package.  Building something from
     other stuff is called a <emphasis>derivation</emphasis> in Nix (as
@@ -76,9 +74,9 @@ the single Nix expression in that directory
     <replaceable>nameN</replaceable> =
     <replaceable>exprN</replaceable>; }</literal>.</para>
 
-  </callout>
+  </listitem>
 
-  <callout arearefs='ex-hello-nix-co-3'>
+  <listitem>
 
     <para>The attribute <varname>name</varname> specifies the symbolic
     name and version of the package.  Nix doesn't really care about
@@ -87,9 +85,9 @@ the single Nix expression in that directory
     packages.  This attribute is required by
     <varname>mkDerivation</varname>.</para>
 
-  </callout>
+  </listitem>
 
-  <callout arearefs='ex-hello-nix-co-4'>
+  <listitem>
 
     <para>The attribute <varname>builder</varname> specifies the
     builder.  This attribute can sometimes be omitted, in which case
@@ -101,9 +99,9 @@ the single Nix expression in that directory
     <command>./builder.sh</command> refers to the shell script shown
     in <xref linkend='ex-hello-builder' />, discussed below.</para>
 
-  </callout>
+  </listitem>
 
-  <callout arearefs='ex-hello-nix-co-5'>
+  <listitem>
 
     <para>The builder has to know what the sources of the package
     are.  Here, the attribute <varname>src</varname> is bound to the
@@ -120,9 +118,9 @@ the single Nix expression in that directory
     customary, and it's also expected by the default builder (which we
     don't use in this example).</para>
 
-  </callout>
+  </listitem>
 
-  <callout arearefs='ex-hello-nix-co-6'>
+  <listitem>
 
     <para>Since the derivation requires Perl, we have to pass the
     value of the <varname>perl</varname> function argument to the
@@ -139,9 +137,9 @@ perl = perl;</programlisting>
     causes the specified attributes to be bound to whatever variables
     with the same name happen to be in scope.</para>
 
-  </callout>
+  </listitem>
 
-</calloutlist>
+</orderedlist>
 
 </para>