nixpkgs/doc/language-support.xml

224 lines
7.3 KiB
XML
Raw Blame History

This file contains ambiguous Unicode characters

This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

<chapter xmlns="http://docbook.org/ns/docbook"
xmlns:xlink="http://www.w3.org/1999/xlink"
xml:id="chap-language-support">
<title>Support for specific programming languages</title>
<para>The <link linkend="chap-stdenv">standard build
environment</link> makes it easy to build typical Autotools-based
packages with very little code. Any other kind of package can be
accomodated by overriding the appropriate phases of
<literal>stdenv</literal>. However, there are specialised functions
in Nixpkgs to easily build packages for other programming languages,
such as Perl or Haskell. These are described in this chapter.</para>
<section xml:id="ssec-language-perl"><title>Perl</title>
<para>Nixpkgs provides a function <varname>buildPerlPackage</varname>,
a generic package builder function for any Perl package that has a
standard <varname>Makefile.PL</varname>. Its implemented in <link
xlink:href="https://github.com/NixOS/nixpkgs/blob/master/pkgs/development/perl-modules/generic"><filename>pkgs/development/perl-modules/generic</filename></link>.</para>
<para>Perl packages from CPAN are defined in <link
xlink:href="https://github.com/NixOS/nixpkgs/blob/master/pkgs/top-level/perl-packages.nix"><filename>pkgs/perl-packages.nix</filename></link>,
rather than <filename>pkgs/all-packages.nix</filename>. Most Perl
packages are so straight-forward to build that they are defined here
directly, rather than having a separate function for each package
called from <filename>perl-packages.nix</filename>. However, more
complicated packages should be put in a separate file, typically in
<filename>pkgs/development/perl-modules</filename>. Here is an
example of the former:
<programlisting>
ClassC3 = buildPerlPackage rec {
name = "Class-C3-0.21";
src = fetchurl {
url = "mirror://cpan/authors/id/F/FL/FLORA/${name}.tar.gz";
sha256 = "1bl8z095y4js66pwxnm7s853pi9czala4sqc743fdlnk27kq94gz";
};
};
</programlisting>
Note the use of <literal>mirror://cpan/</literal>, and the
<literal>${name}</literal> in the URL definition to ensure that the
name attribute is consistent with the source that were actually
downloading. Perl packages are made available in
<filename>all-packages.nix</filename> through the variable
<varname>perlPackages</varname>. For instance, if you have a package
that needs <varname>ClassC3</varname>, you would typically write
<programlisting>
foo = import ../path/to/foo.nix {
inherit stdenv fetchurl ...;
inherit (perlPackages) ClassC3;
};
</programlisting>
in <filename>all-packages.nix</filename>. You can test building a
Perl package as follows:
<screen>
$ nix-build -A perlPackages.ClassC3
</screen>
<varname>buildPerlPackage</varname> adds <literal>perl-</literal> to
the start of the name attribute, so the package above is actually
called <literal>perl-Class-C3-0.21</literal>. So to install it, you
can say:
<screen>
$ nix-env -i perl-Class-C3
</screen>
(Of course you can also install using the attribute name:
<literal>nix-env -i -A perlPackages.ClassC3</literal>.)</para>
<para>So what does <varname>buildPerlPackage</varname> do? It does
the following:
<orderedlist>
<listitem><para>In the configure phase, it calls <literal>perl
Makefile.PL</literal> to generate a Makefile. You can set the
variable <varname>makeMakerFlags</varname> to pass flags to
<filename>Makefile.PL</filename></para></listitem>
<listitem><para>It adds the contents of the <envar>PERL5LIB</envar>
environment variable to <literal>#! .../bin/perl</literal> line of
Perl scripts as <literal>-I<replaceable>dir</replaceable></literal>
flags. This ensures that a script can find its
dependencies.</para></listitem>
<listitem><para>In the fixup phase, it writes the propagated build
inputs (<varname>propagatedBuildInputs</varname>) to the file
<filename>$out/nix-support/propagated-user-env-packages</filename>.
<command>nix-env</command> recursively installs all packages listed
in this file when you install a package that has it. This ensures
that a Perl package can find its dependencies.</para></listitem>
</orderedlist>
</para>
<para><varname>buildPerlPackage</varname> is built on top of
<varname>stdenv</varname>, so everything can be customised in the
usual way. For instance, the <literal>BerkeleyDB</literal> module has
a <varname>preConfigure</varname> hook to generate a configuration
file used by <filename>Makefile.PL</filename>:
<programlisting>
{buildPerlPackage, fetchurl, db4}:
buildPerlPackage rec {
name = "BerkeleyDB-0.36";
src = fetchurl {
url = "mirror://cpan/authors/id/P/PM/PMQS/${name}.tar.gz";
sha256 = "07xf50riarb60l1h6m2dqmql8q5dij619712fsgw7ach04d8g3z1";
};
preConfigure = ''
echo "LIB = ${db4}/lib" > config.in
echo "INCLUDE = ${db4}/include" >> config.in
'';
}
</programlisting>
</para>
<para>Dependencies on other Perl packages can be specified in the
<varname>buildInputs</varname> and
<varname>propagatedBuildInputs</varname> attributes. If something is
exclusively a build-time dependency, use
<varname>buildInputs</varname>; if its (also) a runtime dependency,
use <varname>propagatedBuildInputs</varname>. For instance, this
builds a Perl module that has runtime dependencies on a bunch of other
modules:
<programlisting>
ClassC3Componentised = buildPerlPackage rec {
name = "Class-C3-Componentised-1.0004";
src = fetchurl {
url = "mirror://cpan/authors/id/A/AS/ASH/${name}.tar.gz";
sha256 = "0xql73jkcdbq4q9m0b0rnca6nrlvf5hyzy8is0crdk65bynvs8q1";
};
propagatedBuildInputs = [
ClassC3 ClassInspector TestException MROCompat
];
};
</programlisting>
</para>
</section>
<section><title>Python</title>
<para>
Python packages that
use <link xlink:href="http://pypi.python.org/pypi/setuptools/"><literal>setuptools</literal></link>,
which many Python packages do nowadays, can be built very simply using
the <varname>buildPythonPackage</varname> function. This function is
implemented
in <link xlink:href="https://github.com/NixOS/nixpkgs/blob/master/pkgs/development/python-modules/generic/default.nix"><filename>pkgs/development/python-modules/generic/default.nix</filename></link>
and works similarly to <varname>buildPerlPackage</varname>. (See
<xref linkend="ssec-language-perl"/> for details.)
</para>
<para>
Python packages that use <varname>buildPythonPackage</varname> are
defined
in <link xlink:href="https://github.com/NixOS/nixpkgs/blob/master/pkgs/top-level/python-packages.nix"><filename>pkgs/top-level/python-packages.nix</filename></link>.
Most of them are simple. For example:
<programlisting>
twisted = buildPythonPackage {
name = "twisted-8.1.0";
src = fetchurl {
url = http://tmrc.mit.edu/mirror/twisted/Twisted/8.1/Twisted-8.1.0.tar.bz2;
sha256 = "0q25zbr4xzknaghha72mq57kh53qw1bf8csgp63pm9sfi72qhirl";
};
propagatedBuildInputs = [ pkgs.ZopeInterface ];
meta = {
homepage = http://twistedmatrix.com/;
description = "Twisted, an event-driven networking engine written in Python";
license = "MIT";
};
};
</programlisting>
</para>
</section>
<section><title>Java</title>
<para>Java packages should install JAR files in
<filename>$out/lib/java</filename>.</para>
</section>
<!--
<section><title>Haskell</title>
<para>TODO</para>
</section>
<section><title>TeX / LaTeX</title>
<para>* Special support for building TeX documents</para>
</section>
-->
</chapter>