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-rw-r--r--third_party/nix/doc/manual/expressions/arguments-variables.xml121
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diff --git a/third_party/nix/doc/manual/expressions/arguments-variables.xml b/third_party/nix/doc/manual/expressions/arguments-variables.xml
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--- a/third_party/nix/doc/manual/expressions/arguments-variables.xml
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@@ -1,121 +0,0 @@
-<section xmlns="http://docbook.org/ns/docbook"
-      xmlns:xlink="http://www.w3.org/1999/xlink"
-      xmlns:xi="http://www.w3.org/2001/XInclude"
-      version="5.0"
-      xml:id='sec-arguments'>
-
-<title>Arguments and Variables</title>
-
-<example xml:id='ex-hello-composition'>
-
-<title>Composing GNU Hello
-(<filename>all-packages.nix</filename>)</title>
-<programlisting>
-...
-
-rec { <co xml:id='ex-hello-composition-co-1' />
-
-  hello = import ../applications/misc/hello/ex-1 <co xml:id='ex-hello-composition-co-2' /> { <co xml:id='ex-hello-composition-co-3' />
-    inherit fetchurl stdenv perl;
-  };
-
-  perl = import ../development/interpreters/perl { <co xml:id='ex-hello-composition-co-4' />
-    inherit fetchurl stdenv;
-  };
-
-  fetchurl = import ../build-support/fetchurl {
-    inherit stdenv; ...
-  };
-
-  stdenv = ...;
-
-}
-</programlisting>
-</example>
-
-<para>The Nix expression in <xref linkend='ex-hello-nix' /> is a
-function; it is missing some arguments that have to be filled in
-somewhere.  In the Nix Packages collection this is done in the file
-<filename>pkgs/top-level/all-packages.nix</filename>, where all
-Nix expressions for packages are imported and called with the
-appropriate arguments.  <xref linkend='ex-hello-composition' /> shows
-some fragments of
-<filename>all-packages.nix</filename>.</para>
-
-<calloutlist>
-
-  <callout arearefs='ex-hello-composition-co-1'>
-
-    <para>This file defines a set of attributes, all of which are
-    concrete derivations (i.e., not functions).  In fact, we define a
-    <emphasis>mutually recursive</emphasis> set of attributes.  That
-    is, the attributes can refer to each other.  This is precisely
-    what we want since we want to <quote>plug</quote> the
-    various packages into each other.</para>
-
-  </callout>
-
-  <callout arearefs='ex-hello-composition-co-2'>
-
-    <para>Here we <emphasis>import</emphasis> the Nix expression for
-    GNU Hello.  The import operation just loads and returns the
-    specified Nix expression. In fact, we could just have put the
-    contents of <xref linkend='ex-hello-nix' /> in
-    <filename>all-packages.nix</filename> at this point.  That
-    would be completely equivalent, but it would make the file rather
-    bulky.</para>
-
-    <para>Note that we refer to
-    <filename>../applications/misc/hello/ex-1</filename>, not
-    <filename>../applications/misc/hello/ex-1/default.nix</filename>.
-    When you try to import a directory, Nix automatically appends
-    <filename>/default.nix</filename> to the file name.</para>
-
-  </callout>
-
-  <callout arearefs='ex-hello-composition-co-3'>
-
-    <para>This is where the actual composition takes place.  Here we
-    <emphasis>call</emphasis> the function imported from
-    <filename>../applications/misc/hello/ex-1</filename> with a set
-    containing the things that the function expects, namely
-    <varname>fetchurl</varname>, <varname>stdenv</varname>, and
-    <varname>perl</varname>.  We use inherit again to use the
-    attributes defined in the surrounding scope (we could also have
-    written <literal>fetchurl = fetchurl;</literal>, etc.).</para>
-
-    <para>The result of this function call is an actual derivation
-    that can be built by Nix (since when we fill in the arguments of
-    the function, what we get is its body, which is the call to
-    <varname>stdenv.mkDerivation</varname> in <xref
-    linkend='ex-hello-nix' />).</para>
-
-    <note><para>Nixpkgs has a convenience function
-    <function>callPackage</function> that imports and calls a
-    function, filling in any missing arguments by passing the
-    corresponding attribute from the Nixpkgs set, like this:
-
-<programlisting>
-hello = callPackage ../applications/misc/hello/ex-1 { };
-</programlisting>
-
-    If necessary, you can set or override arguments:
-
-<programlisting>
-hello = callPackage ../applications/misc/hello/ex-1 { stdenv = myStdenv; };
-</programlisting>
-
-    </para></note>
-
-  </callout>
-
-  <callout arearefs='ex-hello-composition-co-4'>
-
-    <para>Likewise, we have to instantiate Perl,
-    <varname>fetchurl</varname>, and the standard environment.</para>
-
-  </callout>
-
-</calloutlist>
-
-</section>
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