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166 lines
No EOL
5 KiB
XML
<chapter xmlns="http://docbook.org/ns/docbook"
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xmlns:xlink="http://www.w3.org/1999/xlink"
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xml:id="chap-meta">
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<title>Support for specific programming languages</title>
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<para>The <link linkend="chap-stdenv">standard build
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environment</link> makes it easy to build typical Autotools-based
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packages with very little code. Any other kind of package can be
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accomodated by overriding the appropriate phases of
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<literal>stdenv</literal>. However, there are specialised functions
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in Nixpkgs to easily build packages for other programming languages,
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such as Perl or Haskell. These are described in this chapter.</para>
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<section><title>Perl</title>
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<para>Nixpkgs provides a function <varname>buildPerlPackage</varname>,
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a generic package builder function for any Perl package that has a
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standard <varname>Makefile.PL</varname>. It’s implemented in <link
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xlink:href="https://svn.nixos.org/repos/nix/nixpkgs/trunk/pkgs/development/perl-modules/generic"><filename>pkgs/development/perl-modules/generic</filename></link>.</para>
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<para>Most Perl packages from CPAN are so straight-forward to build
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that they are defined in <filename>pkgs/all-packages.nix</filename>
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itself. Here is an example:
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<programlisting>
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perlClassC3 = buildPerlPackage rec {
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name = "Class-C3-0.21";
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src = fetchurl {
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url = "mirror://cpan/authors/id/F/FL/FLORA/${name}.tar.gz";
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sha256 = "1bl8z095y4js66pwxnm7s853pi9czala4sqc743fdlnk27kq94gz";
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};
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};
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</programlisting>
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Note the use of <literal>mirror://cpan/</literal>, and the
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<literal>${name}</literal> in the URL definition to ensure that the
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name attribute is consistent with the source that we’re actually
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downloading. As usual, you can test this package as follows:
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<screen>
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$ nix-build -A perlClassC3
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</screen>
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<varname>buildPerlPackage</varname> adds <literal>perl-</literal> to
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the start of the name attribute, so the package above is actually
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called <literal>perl-Class-C3-0.21</literal>. So to install it, you
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can say:
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<screen>
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$ nix-env -i perl-Class-C3
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</screen>
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(Of course you can also install using the attribute name:
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<literal>nix-env -i -A perlClassC3</literal>.)</para>
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<para>So what does <varname>buildPerlPackage</varname> do? It does
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the following:
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<orderedlist>
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<listitem><para>In the configure phase, it calls <literal>perl
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Makefile.PL</literal> to generate a Makefile. You can set the
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variable <varname>makeMakerFlags</varname> to pass flags to
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<filename>Makefile.PL</filename></para></listitem>
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<listitem><para>It adds the contents of the <envar>PERL5LIB</envar>
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environment variable to <literal>#! .../bin/perl</literal> line of
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Perl scripts as <literal>-I<replaceable>dir</replaceable></literal>
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flags. This ensures that a script can find its
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dependencies.</para></listitem>
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<listitem><para>In the fixup phase, it writes the propagated build
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inputs (<varname>propagatedBuildInputs</varname>) to the file
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<filename>$out/nix-support/propagated-user-env-packages</filename>.
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<command>nix-env</command> recursively installs all packages listed
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in this file when you install a package that has it. This ensures
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that a Perl package can find its dependencies.</para></listitem>
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</orderedlist>
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</para>
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<para><varname>buildPerlPackage</varname> is built on top of
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<varname>stdenv</varname>, so everything can be customised in the
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usual way. For instance, the <literal>BerkeleyDB</literal> module has
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a <varname>preConfigure</varname> hook to generate a configuration
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file used by <filename>Makefile.PL</filename>:
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<programlisting>
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{buildPerlPackage, fetchurl, db4}:
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buildPerlPackage rec {
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name = "BerkeleyDB-0.36";
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src = fetchurl {
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url = "mirror://cpan/authors/id/P/PM/PMQS/${name}.tar.gz";
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sha256 = "07xf50riarb60l1h6m2dqmql8q5dij619712fsgw7ach04d8g3z1";
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};
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preConfigure = ''
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echo "LIB = ${db4}/lib" > config.in
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echo "INCLUDE = ${db4}/include" >> config.in
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'';
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}
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</programlisting>
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</para>
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<para>Dependencies on other Perl packages can be specified in the
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<varname>buildInputs</varname> and
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<varname>propagatedBuildInputs</varname> attributes. If something is
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exclusively a build-time dependency, use
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<varname>buildInputs</varname>; if it’s (also) a runtime dependency,
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use <varname>propagatedBuildInputs</varname>. For instance, this
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builds a Perl module that has runtime dependencies on a bunch of other
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modules:
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<programlisting>
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perlClassC3Componentised = buildPerlPackage rec {
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name = "Class-C3-Componentised-1.0004";
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src = fetchurl {
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url = "mirror://cpan/authors/id/A/AS/ASH/${name}.tar.gz";
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sha256 = "0xql73jkcdbq4q9m0b0rnca6nrlvf5hyzy8is0crdk65bynvs8q1";
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};
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propagatedBuildInputs = [
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perlClassC3 perlClassInspector perlTestException perlMROCompat
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];
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};
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</programlisting>
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</para>
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</section>
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<section><title>Python</title>
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<para>TODO</para>
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</section>
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<section><title>Haskell</title>
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<para>TODO</para>
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</section>
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<section><title>Java</title>
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<para>TODO; Java support needs lots of improvement</para>
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</section>
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<section><title>TeX / LaTeX</title>
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<para>* Special support for building TeX documents</para>
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</section>
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</chapter> |