1 <?xml version="1.0" encoding="iso-8859-1"?>
6 <indexterm><primary>packages</primary></indexterm>
8 <para>A package is a library of Haskell modules known to the compiler. GHC
9 comes with several packages: see the accompanying
10 <ulink url="../libraries/index.html">library documentation</ulink>.</para>
12 <para>Using a package couldn't be simpler: if you're using
13 <option>--make</option> or GHCi, then most of the installed packages will be
14 automatically available to your program without any further options. The
15 exceptions to this rule are covered below in <xref
16 linkend="using-packages" />.</para>
18 <para>Building your own packages is also quite straightforward: we provide
19 the <ulink url="http://www.haskell.org/cabal/">Cabal</ulink> infrastructure which
20 automates the process of configuring, building, installing and distributing
21 a package. All you need to do is write a simple configuration file, put a
22 few files in the right places, and you have a package. See the
23 <ulink url="../Cabal/index.html">Cabal documentation</ulink>
24 for details, and also the Cabal libraries (<ulink url="../libraries/Cabal/Distribution.Simple.html">Distribution.Simple</ulink>,
27 <sect2 id="using-packages">
30 <indexterm><primary>packages</primary>
31 <secondary>using</secondary></indexterm>
33 <para>To see which packages are installed, use the
34 <literal>ghc-pkg</literal> command:</para>
38 /usr/lib/ghc-6.4/package.conf:
39 base-1.0, haskell98-1.0, template-haskell-1.0, mtl-1.0, unix-1.0,
40 Cabal-1.0, haskell-src-1.0, parsec-1.0, network-1.0,
41 QuickCheck-1.0, HUnit-1.1, fgl-1.0, X11-1.1, HGL-3.1, OpenGL-2.0,
42 GLUT-2.0, stm-1.0, readline-1.0, (lang-1.0), (concurrent-1.0),
43 (posix-1.0), (util-1.0), (data-1.0), (text-1.0), (net-1.0),
44 (hssource-1.0), rts-1.0
47 <para>Packages are either exposed or hidden. Only
48 modules from exposed packages may be imported by your Haskell code; if
49 you try to import a module from a hidden package, GHC will emit an error
52 <para>Each package has an exposed flag, which says whether it is exposed by
53 default or not. Packages hidden by default are listed in
54 parentheses (eg. <literal>(lang-1.0)</literal>) in the output from
55 <literal>ghc-pkg list</literal>. To expose a package which is hidden by
56 default, use the <option>-package</option>
57 flag (see below).</para>
59 <para>To see which modules are exposed by a package:</para>
62 $ ghc-pkg field network exposed-modules
63 exposed-modules: Network.BSD,
70 <para>In general, packages containing hierarchical modules are usually
71 exposed by default. However, it is possible for two packages to contain
72 the same module: in this case, only one of the packages can be
73 exposed. This might happen if you have two versions of the same package
74 installed, for example. The general rule is:</para>
76 <blockquote><para>There must be no overlaps in the modules provided by all
77 of the exposed packages, and the packages they depend on, and so
78 on.</para></blockquote>
80 <para>The GHC command line options that control packages are:</para>
85 <option>-package <replaceable>P</replaceable></option>
86 <indexterm><primary><option>-package</option></primary></indexterm>
89 <para>This option causes package <replaceable>P</replaceable> to be
90 exposed. The package <replaceable>P</replaceable> can be specified
91 in full with its version number
92 (e.g. <literal>network-1.0</literal>) or the version number can be
93 omitted if there is only one version of the package
96 <para>If there are multiple versions of <replaceable>P</replaceable>
97 installed, then all other versions will become hidden.</para>
99 <para>The <option>-package <replaceable>P</replaceable></option>
100 option also causes package <replaceable>P</replaceable> to be
101 linked into the resulting executable. In
102 <option>––make</option> mode and GHCi, the compiler
103 normally determines which packages are required by the current
104 Haskell modules, and links only those. In batch mode however, the
105 dependency information isn't available, and explicit
106 <option>-package</option> options must be given when linking.</para>
108 <para>For example, to link a program consisting of objects
109 <filename>Foo.o</filename> and <filename>Main.o</filename>, where
110 we made use of the <literal>network</literal> package, we need to
111 give GHC the <literal>-package</literal> flag thus:
113 <screen>$ ghc -o myprog Foo.o Main.o -package network</screen>
115 The same flag is necessary even if we compiled the modules from
116 source, because GHC still reckons it's in batch mode:
118 <screen>$ ghc -o myprog Foo.hs Main.hs -package network</screen>
120 In <literal>--make</literal> and <literal>--interactive</literal>
121 modes (<xref linkend="modes" />), however, GHC figures out the
122 packages required for linking without further assistance.</para>
124 <para>The one other time you might need to use
125 <option>-package</option> to force linking a package is when the
126 package does not contain any Haskell modules (it might contain a C
127 library only, for example). In that case, GHC
128 will never discover a dependency on it, so it has to be mentioned
134 <term><option>-hide-all-packages</option>
135 <indexterm><primary><option>-hide-package</option></primary>
138 <para>Ignore the exposed flag on installed packages, and hide them
139 all by default. If you use
140 this flag, then any packages you require (including
141 <literal>base</literal>) need to be explicitly exposed using
142 <option>-package</option> options.</para>
144 <para>This is a good way to insulate your program from differences
145 in the globally exposed packages, and being explicit about package
146 dependencies is a Good Thing.</para>
151 <term><option>-hide-package</option> <replaceable>P</replaceable>
152 <indexterm><primary><option>-hide-package</option></primary>
155 <para>This option does the opposite of <option>-package</option>: it
156 causes the specified package to be <firstterm>hidden</firstterm>,
157 which means that none of its modules will be available for import
158 by Haskell <literal>import</literal> directives.</para>
160 <para>Note that the package might still end up being linked into the
161 final program, if it is a dependency (direct or indirect) of
162 another exposed package.</para>
167 <term><option>-ignore-package</option> <replaceable>P</replaceable>
168 <indexterm><primary><option>-ignore-package</option></primary>
171 <para>Causes the compiler to behave as if package
172 <replaceable>P</replaceable> is not installed at all. This is not
173 the same as <option>-hide-package</option>, because under
174 <option>-hide-package</option> the package might still be present
175 in the program if another package depends on it.</para>
177 <para><option>-ignore-package</option> <replaceable>P</replaceable>
178 not only causes package <replaceable>P</replaceable> to be removed,
179 but also everything that depends on <replaceable>P</replaceable>,
182 <para>Why do we need <option>-ignore-package</option>? Well, it is
183 particularly useful when you're actually compiling package
184 <replaceable>P</replaceable> itself. The compiler will refuse to
185 compile module <replaceable>M</replaceable> if
186 <replaceable>M</replaceable> is already part of a package. So we
187 might try <option>-hide-package</option>
188 <replaceable>P</replaceable>; but then if
189 <replaceable>P</replaceable> is a dependency of another package
190 <replaceable>P'</replaceable> we would have to
191 <option>-hide-package</option> <replaceable>P'</replaceable> too;
192 and the author of the code can't know in advance which packages are
193 installed on the system and hence which
194 <option>-hide-package</option> flags are required. So, we provide
195 <option>-ignore-package</option> which does the Right Thing.</para>
201 <sect2 id="package-databases">
202 <title>Package Databases</title>
204 <para>A package database is a file, normally called
205 <literal>package.conf</literal> which contains descriptions of installed
206 packages. GHC usually knows about two package databases:</para>
210 <para>The global package database, which comes with your GHC
214 <para>A package database private to each user. On Unix
216 <filename>$HOME/.ghc/<replaceable>arch</replaceable>-<replaceable>os</replaceable>-<replaceable>version</replaceable>/package.conf</filename>, and on
217 Windows it will be something like
218 <filename>C:\Documents And Settings\<replaceable>user</replaceable>\ghc</filename>.
219 The <literal>ghc-pkg</literal> tool knows where this file should be
220 located, and will create it if it doesn't exist (see <xref
221 linkend="package-management" />).</para>
225 <para>When GHC starts up, it reads the contents of these two package
226 databases, and builds up a list of the packages it knows about. You can
227 see GHC's package table by running GHC with the <option>-v</option>
230 <para>Package databases may overlap: for example, packages in the user
231 database will override those of the same name in the global
234 <para>You can control the loading of package databses using the following
240 <option>-package-conf <replaceable>file</replaceable></option>
241 <indexterm><primary><option>-package-conf</option></primary></indexterm>
244 <para>Read in the package configuration file
245 <replaceable>file</replaceable> in addition to the system
246 default file and the user's local file. Packages in additional
247 files read this way will override those in the global and user
253 <term><option>-no-user-package-conf</option>
254 <indexterm><primary><option>-no-user-package-conf</option></primary>
258 <para>Prevent loading of the user's local package database.</para>
263 <para>To create a new package database, just create
264 a new file and put the string
265 <quote><literal>[]</literal></quote> in it. Packages can be
266 added to the file using the
267 <literal>ghc-pkg</literal> tool, described in <xref
268 linkend="package-management"/>.</para>
271 <sect2 id="building-packages">
272 <title>Building a package from Haskell source</title>
273 <indexterm><primary>packages</primary>
274 <secondary>building</secondary></indexterm>
276 <para>We don't recommend building packages the hard way. Instead, use the
277 <ulink url="../Cabal/index.html">Cabal</ulink> infrastructure
278 if possible. If your package is particularly complicated or requires a
279 lot of configuration, then you might have to fall back to the low-level
280 mechanisms, so a few hints for those brave souls follow.</para>
284 <para>You need to build an "installed package info" file for
285 passing to <literal>ghc-pkg</literal> when installing your
286 package. The contents of this file are described in <xref
287 linkend="installed-pkg-info" />.</para>
291 <para>The Haskell code in a package may be built into one or
292 more archive libraries
293 (e.g. <filename>libHSfoo.a</filename>), or a single DLL on
294 Windows (e.g. <filename>HSfoo.dll</filename>). The
295 restriction to a single DLL on Windows is because the
296 package system is used to tell the compiler when it should
297 make an inter-DLL call rather than an intra-DLL call
298 (inter-DLL calls require an extra
299 indirection). <emphasis>Building packages as DLLs doesn't
300 work at the moment; see <xref linkend="win32-dlls-create"/>
301 for the gory details.</emphasis>
304 <para>Building a static library is done by using the
305 <literal>ar</literal> tool, like so:</para>
307 <screen>ar cqs libHSfoo.a A.o B.o C.o ...</screen>
309 <para>where <filename>A.o</filename>,
310 <filename>B.o</filename> and so on are the compiled Haskell
311 modules, and <filename>libHSfoo.a</filename> is the library
312 you wish to create. The syntax may differ slightly on your
313 system, so check the documentation if you run into
316 <para>Versions of the Haskell libraries for use with GHCi
317 may also be included: GHCi cannot load <literal>.a</literal>
318 files directly, instead it will look for an object file
319 called <filename>HSfoo.o</filename> and load that. On some
320 systems, the <literal>ghc-pkg</literal> tool can
321 automatically build the GHCi version of each library, see
322 <xref linkend="package-management"/>. To build these
323 libraries by hand from the <literal>.a</literal> archive, it
324 is possible to use GNU <command>ld</command> as
327 <screen>ld -r ––whole-archive -o HSfoo.o libHSfoo.a</screen>
330 <literal>––--whole-archive</literal> with
331 <literal>–all_load</literal> on MacOS X)</para>
333 <para>GHC does not maintain detailed cross-package
334 dependency information. It does remember which modules in
335 other packages the current module depends on, but not which
336 things within those imported things.</para>
340 <para>When compiling a Haskell module which is to be part of a new package
341 <replaceable>P</replaceable>, use
342 <option>-ignore-package</option> <replaceable>P</replaceable>.</para>
346 <para>It is worth noting that on Windows, when each package
347 is built as a DLL, since a reference to a DLL costs an extra
348 indirection, intra-package references are cheaper than
349 inter-package references. Of course, this applies to the
350 <filename>Main</filename> package as well.</para>
353 <sect2 id="package-management">
354 <title>Package management (the <literal>ghc-pkg</literal> command)</title>
355 <indexterm><primary>packages</primary>
356 <secondary>management</secondary></indexterm>
358 <para>The <literal>ghc-pkg</literal> tool allows packages to be
359 added or removed from a package database. By default,
360 the system-wide package database is modified, but alternatively
361 the user's local package database or another specified
362 file can be used.</para>
364 <para>Commands which only inspect the database (<literal>list</literal>,
365 <literal>describe</literal>, <literal>field</literal>) will take into
366 account the user's local package database too, unless the
367 <literal>--global</literal> option is given. This matches the behaviour
368 of GHC, which automatically reads the user's local database if it is
371 <para>The <literal>ghc-pkg</literal> program may be run in the ways listed
372 below. Where a package name is required, the package can be named in
373 full including the version number
374 (e.g. <literal>network-1.0</literal>), or without the version number if
375 there is only a single version of that package installed. Additionally,
376 the version may be given as <literal>*</literal>, which means “all
377 versions”. For example, <literal>ghc-pkg hide network-*</literal>
378 would hide all versions of the network package.</para>
382 <term><literal>ghc-pkg register <replaceable>file</replaceable></literal></term>
384 <para>Reads a package specification from
385 <replaceable>file</replaceable> (which may be “<literal>-</literal>”
386 to indicate standard input),
387 and adds it to the database of installed packages. The syntax of
388 <replaceable>file</replaceable> is given in <xref
389 linkend="installed-pkg-info" />.</para>
391 <para>The package specification must be a package that isn't already
397 <term><literal>ghc-pkg update <replaceable>file</replaceable></literal></term>
399 <para>The same as <literal>register</literal>, except that if a
400 package of the same name is already installed, it is
401 replaced by the new one.</para>
406 <term><literal>ghc-pkg unregister <replaceable>P</replaceable></literal></term>
408 <para>Remove the specified package from the database.</para>
413 <term><literal>ghc-pkg expose <replaceable>P</replaceable></literal></term>
415 <para>Sets the <literal>exposed</literal> flag for package
416 <replaceable>P</replaceable> to <literal>True</literal>.</para>
421 <term><literal>ghc-pkg hide <replaceable>P</replaceable></literal></term>
423 <para>Sets the <literal>exposed</literal> flag for package
424 <replaceable>P</replaceable> to <literal>False</literal>.</para>
429 <term><literal>ghc-pkg list</literal></term>
431 <para>This option displays the currently installed
432 packages, for each of the databases known to
433 <literal>ghc-pkg</literal>. That includes the global database, the
434 user's local database (if <option>--user</option> is given), and
435 any further files specified using the <option>-f</option> option on
436 the command line.</para>
438 <para>Hidden packages (those for which the <literal>exposed</literal>
439 flag is <literal>False</literal>) are shown in parentheses in the
440 list of packages.</para>
445 <term><literal>ghc-pkg describe <replaceable>P</replaceable></literal></term>
447 <para>Emit the full description of the specified package. The
448 description is in the form of an
449 <literal>InstalledPackageInfo</literal>, the same as the input file
450 format for <literal>ghc-pkg register</literal>. See <xref
451 linkend="installed-pkg-info" /> for details.</para>
456 <term><literal>ghc-pkg field <replaceable>P</replaceable> <replaceable>field</replaceable></literal></term>
458 <para>Show just a single field of the installed package description
459 for <literal>P</literal>.</para>
464 <para>Additionally, the following flags are accepted by
465 <literal>ghc-pkg</literal>:</para>
470 <option>––auto-ghci-libs</option><indexterm><primary><option>––user</option></primary>
474 <para>Automatically generate the GHCi
475 <filename>.o</filename> version of each
476 <filename>.a</filename> Haskell library, using GNU ld (if
477 that is available). Without this option,
478 <literal>ghc-pkg</literal> will warn if GHCi versions of
479 any Haskell libraries in the package don't exist.</para>
481 <para>GHCi <literal>.o</literal> libraries don't
482 necessarily have to live in the same directory as the
483 corresponding <literal>.a</literal> library. However,
484 this option will cause the GHCi library to be created in
485 the same directory as the <literal>.a</literal>
492 <option>-f</option> <replaceable>file</replaceable>
493 <indexterm><primary><option>-f</option></primary>
497 <option>-package-conf</option> <replaceable>file</replaceable>
498 <indexterm><primary><option>-package-conf</option></primary>
502 <para>Operate on the package database in
503 <replaceable>file</replaceable>.</para>
505 <para>When multiple <option>-f</option> options are given, or
506 <option>-f</option> is used in conjunction with
507 <option>--user</option> or <option>--global</option>, the last
508 one on the command-line is the one that will be modified.</para>
514 <option>––force</option>
516 <option>––force</option>
517 </primary></indexterm>
520 <para>Causes <literal>ghc-pkg</literal> to ignore missing
521 dependencies, directories and libraries when registering a package,
522 and just go ahead and add it anyway. This might be useful if your
523 package installation system needs to add the package to
524 GHC before building and installing the files.</para>
530 <option>––global</option><indexterm><primary><option>––user</option></primary>
534 <para>Operate on the global package database (this is the default).
535 This flag affects the <literal>register</literal>,
536 <literal>update</literal>, <literal>unregister</literal>,
537 <literal>expose</literal>, and <literal>hide</literal>
544 <option>––help</option><indexterm><primary><option>––user</option></primary>
548 <option>-?</option><indexterm><primary><option>-?</option></primary>
552 <para>Outputs the command-line syntax.</para>
558 <option>––user</option><indexterm><primary><option>––user</option></primary>
562 <para>Operate on the current user's local package database.
563 This flag affects the <literal>register</literal>,
564 <literal>update</literal>, <literal>unregister</literal>,
565 <literal>expose</literal>, and <literal>hide</literal>
572 <option>-V</option><indexterm><primary><option>-V</option></primary>
576 <option>––version</option><indexterm><primary><option>––user</option></primary>
580 <para>Output the <literal>ghc-pkg</literal> version number.</para>
585 <para>When modifying the package database
586 <replaceable>file</replaceable>, a copy of the original file is
587 saved in <replaceable>file</replaceable><literal>.old</literal>,
588 so in an emergency you can always restore the old settings by
589 copying the old file back again.</para>
593 <sect2 id="installed-pkg-info">
595 <literal>InstalledPackageInfo</literal>: a package specification
598 <para>A package specification is a Haskell record; in particular, it is the
600 url="../libraries/Cabal/Distribution.InstalledPackageInfo.html#%tInstalledPackageInfo">InstalledPackageInfo</ulink> in the module Distribution.InstalledPackageInfo, which is part of the Cabal package distributed with GHC.</para>
602 <para>An <literal>InstalledPackageInfo</literal> has a human
603 readable/writable syntax. The functions
604 <literal>parseInstalledPackageInfo</literal> and
605 <literal>showInstalledPackageInfo</literal> read and write this syntax
606 respectively. Here's an example of the
607 <literal>InstalledPackageInfo</literal> for the <literal>unix</literal> package:</para>
610 $ ghc-pkg describe unix
615 maintainer: libraries@haskell.org
623 exposed-modules: System.Posix,
624 System.Posix.DynamicLinker.Module,
625 System.Posix.DynamicLinker.Prim,
626 System.Posix.Directory,
627 System.Posix.DynamicLinker,
632 System.Posix.Process,
633 System.Posix.Resource,
635 System.Posix.Terminal,
639 System.Posix.Signals.Exts
640 import-dirs: /usr/lib/ghc-6.4/libraries/unix
641 library-dirs: /usr/lib/ghc-6.4/libraries/unix
643 extra-libs: HSunix_cbits, dl
644 include-dirs: /usr/lib/ghc-6.4/libraries/unix/include
649 <para>The full <ulink url="../Cabal/index.html">Cabal documentation</ulink>
650 is still in preparation (at time of writing), so in the meantime
651 here is a brief description of the syntax of this file:</para>
653 <para>A package description consists of a number of field/value pairs. A
654 field starts with the field name in the left-hand column followed by a
655 “<literal>:</literal>”, and the value continues until the next line that begins in the
656 left-hand column, or the end of file.</para>
658 <para>The syntax of the value depends on the field. The various field
663 <term>freeform</term>
665 <para>Any arbitrary string, no interpretation or parsing is
672 <para>A sequence of non-space characters, or a sequence of arbitrary
673 characters surrounded by quotes <literal>"...."</literal>.</para>
677 <term>string list</term>
679 <para>A sequence of strings, separated by commas. The sequence may
685 <para>In addition, there are some fields with special syntax (e.g. package
686 names, version, dependencies).</para>
688 <para>The allowed fields, with their types, are:</para>
693 <literal>name</literal>
694 <indexterm><primary><literal>name</literal></primary><secondary>package specification</secondary></indexterm>
697 <para>The package's name (without the version).</para>
703 <literal>version</literal>
704 <indexterm><primary><literal>version</literal></primary><secondary>package specification</secondary></indexterm>
707 <para>The package's version, usually in the form
708 <literal>A.B</literal> (any number of components are allowed).</para>
714 <literal>license</literal>
715 <indexterm><primary><literal>auto</literal></primary><secondary>package specification</secondary></indexterm>
718 <para>(string) The type of license under which this package is distributed.
719 This field is a value of the <ulink
720 url="../libraries/Cabal/Distribution.License.html#t:License"><literal>License</literal></ulink> type.</para>
726 <literal>license-file</literal>
727 <indexterm><primary><literal>license-file</literal></primary><secondary>package specification</secondary></indexterm>
730 <para>(optional string) The name of a file giving detailed license
731 information for this package.</para>
737 <literal>copyright</literal>
738 <indexterm><primary><literal>copyright</literal></primary><secondary>package specification</secondary></indexterm>
741 <para>(optional freeform) The copyright string.</para>
747 <literal>maintainer</literal>
748 <indexterm><primary><literal>maintainer</literal></primary><secondary>package specification</secondary></indexterm>
751 <para>(optinoal freeform) The email address of the package's maintainer.</para>
757 <literal>stability</literal>
758 <indexterm><primary><literal>stability</literal></primary><secondary>package specification</secondary></indexterm>
761 <para>(optional freeform) A string describing the stability of the package
762 (eg. stable, provisional or experimental).</para>
768 <literal>homepage</literal>
769 <indexterm><primary><literal>homepage</literal></primary><secondary>package specification</secondary></indexterm>
772 <para>(optional freeform) URL of the package's home page.</para>
778 <literal>package-url</literal>
779 <indexterm><primary><literal>package-url</literal></primary><secondary>package specification</secondary></indexterm>
782 <para>(optional freeform) URL of a downloadable distribution for this
783 package. The distribution should be a Cabal package.</para>
789 <literal>description</literal>
790 <indexterm><primary><literal>description</literal></primary><secondary>package specification</secondary></indexterm>
793 <para>(optional freeform) Description of the package.</para>
799 <literal>category</literal>
800 <indexterm><primary><literal>category</literal></primary><secondary>package specification</secondary></indexterm>
803 <para>(optinoal freeform) Which category the package belongs to. This field
804 is for use in conjunction with a future centralised package
805 distribution framework, tentatively titled Hackage.</para>
811 <literal>author</literal>
812 <indexterm><primary><literal>author</literal></primary><secondary>package specification</secondary></indexterm>
815 <para>(optional freeform) Author of the package.</para>
821 <literal>exposed</literal>
822 <indexterm><primary><literal>exposed</literal></primary><secondary>package specification</secondary></indexterm>
825 <para>(bool) Whether the package is exposed or not.</para>
831 <literal>exposed-modules</literal>
832 <indexterm><primary><literal>exposed-modules</literal></primary><secondary>package specification</secondary></indexterm>
835 <para>(string list) modules exposed by this package.</para>
841 <literal>hidden-modules</literal>
842 <indexterm><primary><literal>hidden-modules</literal></primary><secondary>package specification</secondary></indexterm>
845 <para>(string list) modules provided by this package,
846 but not exposed to the programmer. These modules cannot be
847 imported, but they are still subject to the overlapping constraint:
848 no other package in the same program may provide a module of the
855 <literal>import-dirs</literal>
856 <indexterm><primary><literal>import-dirs</literal></primary><secondary>package specification</secondary></indexterm>
859 <para>(string list) A list of directories containing interface files
860 (<literal>.hi</literal> files) for this package.</para>
862 <para>If the package contains profiling libraries, then
863 the interface files for those library modules should have
864 the suffix <literal>.p_hi</literal>. So the package can
865 contain both normal and profiling versions of the same
866 library without conflict (see also
867 <literal>library_dirs</literal> below).</para>
873 <literal>library-dirs</literal>
874 <indexterm><primary><literal>library-dirs</literal></primary><secondary>package specification</secondary></indexterm>
877 <para>(string list) A list of directories containing libraries for this
884 <literal>hs-libraries</literal>
885 <indexterm><primary><literal>hs-libraries</literal></primary><secondary>package specification</secondary></indexterm>
888 <para>(string list) A list of libraries containing Haskell code for this
889 package, with the <literal>.a</literal> or
890 <literal>.dll</literal> suffix omitted. When packages are
891 built as libraries, the
892 <literal>lib</literal> prefix is also omitted.</para>
894 <para>For use with GHCi, each library should have an
895 object file too. The name of the object file does
896 <emphasis>not</emphasis> have a <literal>lib</literal>
897 prefix, and has the normal object suffix for your
900 <para>For example, if we specify a Haskell library as
901 <filename>HSfoo</filename> in the package spec, then the
902 various flavours of library that GHC actually uses will be
906 <term><filename>libHSfoo.a</filename></term>
908 <para>The name of the library on Unix and Windows
909 (mingw) systems. Note that we don't support
910 building dynamic libraries of Haskell code on Unix
915 <term><filename>HSfoo.dll</filename></term>
917 <para>The name of the dynamic library on Windows
918 systems (optional).</para>
922 <term><filename>HSfoo.o</filename></term>
923 <term><filename>HSfoo.obj</filename></term>
925 <para>The object version of the library used by
935 <literal>extra-libs</literal>
936 <indexterm><primary><literal>extra-libs</literal></primary><secondary>package specification</secondary></indexterm>
939 <para>(string list) A list of extra libraries for this package. The
940 difference between <literal>hs-libraries</literal> and
941 <literal>extra-libs</literal> is that
942 <literal>hs-libraries</literal> normally have several
943 versions, to support profiling, parallel and other build
944 options. The various versions are given different
945 suffixes to distinguish them, for example the profiling
946 version of the standard prelude library is named
947 <filename>libHSbase_p.a</filename>, with the
948 <literal>_p</literal> indicating that this is a profiling
949 version. The suffix is added automatically by GHC for
950 <literal>hs-libraries</literal> only, no suffix is added
952 <literal>extra-libs</literal>.</para>
954 <para>The libraries listed in
955 <literal>extra-libs</literal> may be any libraries
956 supported by your system's linker, including dynamic
957 libraries (<literal>.so</literal> on Unix,
958 <literal>.DLL</literal> on Windows).</para>
960 <para>Also, <literal>extra-libs</literal> are placed
961 on the linker command line after the
962 <literal>hs-libraries</literal> for the same package. If
963 your package has dependencies in the other direction (i.e.
964 <literal>extra-libs</literal> depends on
965 <literal>hs-libraries</literal>), and the libraries are
966 static, you might need to make two separate
973 <literal>include-dirs</literal>
974 <indexterm><primary><literal>include-dirs</literal></primary><secondary>package specification</secondary></indexterm>
977 <para>(string list) A list of directories containing C includes for this
984 <literal>includes</literal>
985 <indexterm><primary><literal>includes</literal></primary><secondary>package specification</secondary></indexterm>
988 <para>(string list) A list of files to include for via-C compilations
989 using this package. Typically the include file(s) will
990 contain function prototypes for any C functions used in
991 the package, in case they end up being called as a result
992 of Haskell functions from the package being
999 <literal>depends</literal>
1000 <indexterm><primary><literal>depends</literal></primary><secondary>package specification</secondary></indexterm>
1003 <para>(package name list) Packages on which this package depends. This field contains
1004 packages with explicit versions are required, except that when
1005 submitting a package to <literal>ghc-pkg register</literal>, the
1006 versions will be filled in if they are unambiguous.</para>
1012 <literal>extra-hugs-opts</literal>
1013 <indexterm><primary><literal>extra-hugs-opts</literal></primary><secondary>package specification</secondary></indexterm>
1016 <para>(string list) Options to pass to Hugs for this package.</para>
1022 <literal>extra-cc-opts</literal>
1023 <indexterm><primary><literal>extra-cc-opts</literal></primary><secondary>package specification</secondary></indexterm>
1026 <para>(string list) Extra arguments to be added to the gcc command line
1027 when this package is being used (only for via-C
1028 compilations).</para>
1034 <literal>extra-ld-opts</literal>
1035 <indexterm><primary><literal>extra-ld-opts</literal></primary><secondary>package specification</secondary></indexterm>
1038 <para>(string list) Extra arguments to be added to the
1039 <command>gcc</command> command line (for linking) when
1040 this package is being used.</para>
1046 <literal>framework-dirs</literal>
1047 <indexterm><primary><literal>framework-dirs</literal></primary><secondary>package specification</secondary></indexterm>
1050 <para>(string list) On Darwin/MacOS X, a list of directories containing
1051 frameworks for this package. This corresponds to the
1052 <option>-framework-path</option> option. It is ignored on all other
1059 <literal>extra-frameworks</literal>
1060 <indexterm><primary><literal>extra-frameworks</literal></primary><secondary>package specification</secondary></indexterm>
1063 <para>(string list) On Darwin/MacOS X, a list of frameworks to link to. This
1064 corresponds to the <option>-framework</option> option. Take a look
1065 at Apple's developer documentation to find out what frameworks
1066 actually are. This entry is ignored on all other platforms.</para>
1072 <literal>haddock-interfaces</literal>
1073 <indexterm><primary><literal>haddock-interfaces</literal></primary><secondary>package specification</secondary></indexterm>
1076 <para>(string list) A list of filenames containing <ulink
1077 url="http://www.haskell.org/haddock/">Haddock</ulink> interface
1078 files (<literal>.haddock</literal> files) for this package.</para>
1084 <literal>haddock-html</literal>
1085 <indexterm><primary><literal>haddock-html</literal></primary><secondary>package specification</secondary></indexterm>
1088 <para>(optional string) The directory containing the Haddock-generated HTML
1089 for this package.</para>
1094 <!-- This isn't true any more. I'm not sure if we still need it -SDM
1096 The <literal>ghc-pkg</literal> tool performs expansion of
1097 environment variables occurring in input package specifications.
1098 So, if the <literal>mypkg</literal> was added to the package
1099 database as follows:
1102 $ installdir=/usr/local/lib ghc-pkg -a < mypkg.pkg
1106 The occurrence of <literal>${installdir}</literal> is replaced
1107 with <literal>/usr/local/lib</literal> in the package data that
1108 is added for <literal>mypkg</literal>.
1112 This feature enables the distribution of package specification
1113 files that can be easily configured when installing.
1116 <para>For examples of more package specifications, take a look
1117 at the <literal>package.conf</literal> in your GHC
1118 installation.</para>
1126 ;;; Local Variables: ***
1128 ;;; sgml-parent-document: ("users_guide.xml" "book" "chapter" "sect1") ***