GF Developers Guide
Authors: Björn Bringert, Krasimir Angelov and Thomas Hallgren
Last update: %%mtime(%F, %H:%M)

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== Before you start ==

This guide is intended for people who want to contribute to
the development of the GF compiler or the Resource Grammar Library. If
you are a GF user who just wants to download and install GF
(e.g to develop your own grammars), the simpler guide on
[the GF download page ../download/index.html] should be sufficient.

== Setting up your system for building GF ==

To build GF from source you need to install some tools on your
system: the //Haskell Platform//, //Git// and the //Haskeline library//.

**On Linux** the best option is to install the tools via the standard
software distribution channels, i.e. by using the //Software Center//
in Ubuntu or the corresponding tool in other popular Linux distributions.
Or, from a Terminal window, the following command should be enough:

- On Ubuntu: ``sudo apt-get install haskell-platform git libghc6-haskeline-dev``
- On Fedora: ``sudo dnf install haskell-platform git ghc-haskeline-devel``


**On Mac OS and Windows**, the tools can be downloaded from their respective
web sites, as described below.

=== The Haskell Platform ===

GF is written in Haskell, so first of all you need
the //Haskell Platform//, e.g. version 8.0.2 or 7.10.3. Downloads
and installation instructions are available from here:

    http://hackage.haskell.org/platform/

Once you have installed the Haskell Platform, open a terminal
(Command Prompt on Windows) and try to execute the following command:
```
$ ghc --version
```
This command should show you which version of GHC you have. If the installation
of the Haskell Platform	 was successful you should see a message like:

```
The Glorious Glasgow Haskell Compilation System, version 8.0.2
```

Other required tools included in the Haskell Platform are 
[Cabal http://www.haskell.org/cabal/],
[Alex http://www.haskell.org/alex/]
and
[Happy http://www.haskell.org/happy/].

%=== Darcs ===
%
%To get the GF source code, you also need //Darcs//, version 2 or later.
%Darcs 2.10 is recommended (July 2015).
%
%//Darcs//
%is a distributed version control system, see http://darcs.net/ for
%more information. There are precompiled packages for many platforms
%available and source code if you want to compile it yourself. Darcs
%is also written in Haskell and so you can use GHC to compile it.


=== Git ===

To get the GF source code, you also need //Git//.
//Git// is a distributed version control system, see
https://git-scm.com/downloads for more information.

=== The haskeline library ===

GF uses //haskeline// to enable command line editing in the GF shell.
This should work automatically on Mac OS and Windows, but on Linux one
extra step is needed to make sure the C libraries (terminfo)
required by //haskeline// are installed.  Here is one way to do this:

- On Ubuntu: ``sudo apt-get install libghc-haskeline-dev``
- On Fedora: ``sudo dnf install ghc-haskeline-devel``


== Getting the source ==

Once you have all tools in place you can get the GF source code. If you
just want to compile and use GF then it is enough to have read-only
access. It is also possible to make changes in the source code but if you
want these changes to be applied back to the main source repository you will
have to send the changes to us.  If you plan to work continuously on
GF then you should consider getting read-write access.

=== Read-only access ===

==== Getting a fresh copy for read-only access ====

Anyone can get the latest development version of GF by running (all on one line):

```
$ git clone https://github.com/GrammaticalFramework/GF.git
```

This will create a directory called ``GF`` in the current
directory.


==== Updating your copy ====

To get all new patches from the main repo:
```
$ git pull
```
This can be done anywhere in your local repository, i.e. in the ``gf``
directory, or any of its subdirectories.


==== Recording local changes ====[record]

Since every copy is a repository, you can have local version control
of your changes.

If you have added files, you first need to tell your local repository to 
keep them under revision control:

```
$ git add file1 file2 ...
```

To record changes, use:

```
$ git commit file1 file2 ...
```

This creates a patch against the previous version and stores it in your
local repository. You can record any number of changes before
pushing them to the main repo. In fact, you don't have to push them at
all if you want to keep the changes only in your local repo.

Instead of enumerating all modified files on the command line,
you can use the flag ``-a`` to automatically record //all// modified
files. You still need to use ``git add`` to add new files.


%==== Submitting patches ====
%
%If you are using read-only access, send your patches by email to
%someone with write-access. First record your changes in your local 
%repository, as described above. You can send any number of recorded
%patches as one patch bundle. You create the patch bundle with:
%
%```
%$ darcs send -o mypatch.patch
%$ gzip mypatch.patch
%```
%
%(where ``mypatch`` is hopefully replaced by a slightly more
%descriptive name). Since some e-mail setups change text attachments
%(most likely by changing the newline characters) you need to send
%the patch in some compressed format, such as GZIP, BZIP2 or ZIP.
%
%Send it as an e-mail attachment.
%% If you have
%%sendmail or something equivalent installed, it is possible to send the
%%patch directly from darcs. If so, replace ``-o mypatch.patch`` with
%%``--to=EMAIL`` where ``EMAIL`` is the address to send it to.


=== Read-write access ===

If you are a member of the GF project on GitHub, you can push your
changes directly to the GF git repository on GitHub.

```
$ git push
```

It is also possible for anyone else to contribute by

- creating a fork of the GF repository on GitHub,
- working with local clone of the fork (obtained with ``git clone``),
- pushing changes to the fork,
- and finally sending a pull request.



== Compilation from source with Cabal ==

The build system of GF is based on //Cabal//, which is part of the
Haskell Platform, so no extra steps are needed to install it. In the simplest
case, all you need to do to compile and install GF, after downloading the
source code as described above, is

```
$ cd gf
$ cabal install
```

This will automatically download any additional Haskell libraries needed to
build GF. If this is the first time you use Cabal, you might need to run
``cabal update`` first, to update the list of available libraries.

If you want more control, the process can also be split up into the usual
//configure//, //build// and //install// steps.

=== Configure ===

During the configuration phase Cabal will check that you have all
necessary tools and libraries needed for GF. The configuration is
started by the command:

```
$ cabal configure
```

If you don't see any error message from the above command then you
have everything that is needed for GF. You can also add the option
``-v`` to see more details about the configuration.

You can use ``cabal configure --help`` to get a list of configuration options.

=== Build ===

The build phase does two things. First it builds the GF compiler from
the Haskell source code and after that it builds the GF Resource Grammar
Library using the already build compiler.  The simplest command is:

```
$ cabal build
```

Again you can add the option ``-v`` if you want to see more details.

==== Parallel builds ====

If you have Cabal>=1.20 you can enable parallel compilation by using

```
$ cabal build -j
```

or by putting a line
```
jobs: $ncpus
```
in your ``.cabal/config`` file. Cabal
will pass this option to GHC when building the GF compiler, if you
have GHC>=7.8.

Cabal also passes ``-j`` to GF to enable parallel compilation of the
Resource Grammar Library. This is done unconditionally to avoid
causing problems for developers with Cabal<1.20. You can disable this
by editing the last few lines in ``WebSetup.hs``.


==== Partial builds ====

**NOTE**: The following doesn't work with recent versions of ``cabal``.
%% // TH 2015-06-22

Sometimes you just want to work on the GF compiler and don't want to
recompile the resource library after each change. In this case use
this extended command:

```
$ cabal build rgl-none
```

The resource library could also be compiled in two modes: with present
tense only and with all tenses. By default it is compiled with all
tenses. If you want to use the library with only present tense you can
compile it in this special mode with the command:

```
$ cabal build present
```

You could also control which languages you want to be recompiled by
adding the option ``langs=list``. For example the following command
will compile only the English and the Swedish language:

```
$ cabal build langs=Eng,Swe
```

=== Install ===

After you have compiled GF you need to install the executable and libraries
to make the system usable.

```
$ cabal copy
$ cabal register
```

This command installs the GF compiler for a single user, in the standard
place used by Cabal.
On Linux and Mac this could be ``$HOME/.cabal/bin``.
On Mac it could also be ``$HOME/Library/Haskell/bin``.
On Windows this is ``C:\Program Files\Haskell\bin``.

The compiled GF Resource Grammar Library will be installed
under the same prefix, e.g. in
``$HOME/.cabal/share/gf-3.3.3/lib`` on Linux and
in ``C:\Program Files\Haskell\gf-3.3.3\lib`` on Windows.

If you want to install in some other place then use the ``--prefix``
option during the configuration phase.

=== Clean ===

Sometimes you want to clean up the compilation and start again from clean
sources. Use the clean command for this purpose:

```
$ cabal clean
```


%=== SDist ===
%
%You can use the command:
%
%% This does *NOT* include everything that is needed // TH 2012-08-06
%```
%$ cabal sdist
%```
%
%to prepare archive with all source codes needed to compile GF.

=== Known problems with Cabal ===

Some versions of Cabal (at least version 1.16) seem to have a bug that can
cause the following error:

```
Configuring gf-3.x...
setup: Distribution/Simple/PackageIndex.hs:124:8-13: Assertion failed
```

The exact cause of this problem is unclear, but it seems to happen
during the configure phase if the same version of GF is already installed,
so a workaround is to remove the existing installation with

```
ghc-pkg unregister gf
```

You can check with ``ghc-pkg list gf`` that it is gone.

== Compilation with make ==

If you feel more comfortable with Makefiles then there is a thin Makefile
wrapper arround Cabal for you. If you just type:
```
$ make
```
the configuration phase will be run automatically if needed and after that
the sources will be compiled.

%% cabal build rgl-none does not work with recent versions of Cabal
%If you don't want to compile the resource library
%every time then you can use:
%```
%$ make gf
%```

For installation use:
```
$ make install
```
For cleaning:
```
$ make clean
```
%and to build source distribution archive run:
%```
%$ make sdist
%```

== Compiling GF with C run-time system support ==

The C run-time system is a separate implementation of the PGF run-time services.
It makes it possible to work with very large, ambiguous grammars, using
probabilistic models to obtain probable parses. The C run-time system might
also be easier to use than the Haskell run-time system on certain platforms,
e.g. Android and iOS.

To install the C run-time system, go to the ``src/runtime/c`` directory
%and follow the instructions in the ``INSTALL`` file.
and use the ``install.sh`` script:
```
bash setup.sh configure
bash setup.sh build
bash setup.sh install
```
This will install
the C header files and libraries need to write C programs that use PGF grammars.
Some example C programs are included in the ``utils`` subdirectory, e.g.
``pgf-translate.c``.

When the C run-time system is installed, you can install GF with C run-time
support by doing

```
cabal install -fserver -fc-runtime
```
from the top directory. This give you three new things:

- ``PGF2``: a module to import in Haskell programs, providing a binding to
   the C run-time system.

- The GF shell can be started with ``gf -cshell`` or ``gf -crun`` to use
  the C run-time system instead of the Haskell run-time system.
  Only limited functionality is available when running the shell in these
  modes (use the ``help`` command in the shell for details).

- ``gf -server`` mode is extended with new requests to call the C run-time
   system, e.g. ``c-parse``, ``c-linearize`` and ``c-translate``.


=== Python and Java bindings ===

The C run-time system can also be used from Python and Java. Python and Java
bindings are found in the ``src/runtime/python`` and ``src/runtime/java``
directories, respecively. Compile them by following the instructions in
the ``INSTALL`` files in those directories.


== Creating binary distribution packages ==

=== Creating .deb packages for Ubuntu ===

This was tested on Ubuntu 14.04 for the release of GF 3.6, and the
resulting ``.deb`` packages appears to work on Ubuntu 12.04, 13.10 and 14.04.
For the release of GF 3.7, we generated ``.deb`` packages on Ubuntu 15.04 and
tested them on Ubuntu 12.04 and 14.04.

Under Ubuntu, Haskell executables are statically linked against other Haskell
libraries, so the .deb packages are fairly self-contained.

==== Preparations ====

```
sudo apt-get install dpkg-dev debhelper
```

==== Creating the package ====

Make sure the ``debian/changelog`` starts with an entry that describes the
version you are building. Then run

```
make deb
```

If get error messages about missing dependencies
(e.g. ``autoconf``, ``automake``, ``libtool-bin``, ``python-dev``,
``java-sdk``, ``txt2tags``)
use ``apt-get intall`` to install them, then try again.


=== Creating OS X Installer packages ===

Run

```
make pkg
```

=== Creating binary tar distributions ===

Run

```
make bintar
```

=== Creating .rpm packages for Fedora ===

This is possible, but the procedure has not been automated.
It involves using the cabal-rpm tool,

```
sudo dnf install cabal-rpm
```

and following the Fedora guide
[How to create an RPM package http://fedoraproject.org/wiki/How_to_create_an_RPM_package].

Under Fedora, Haskell executables are dynamically linked against other Haskell
libraries, so ``.rpm`` packages for all Haskell libraries that GF depends on
are required. Most of them are already available in the Fedora distribution,
but a few of them might have to be built and distributed along with
the GF ``.rpm`` package.
When building ``.rpm`` packages for GF 3.4, we also had to build ``.rpm``s for
``fst`` and ``httpd-shed``.

== Running the testsuite ==

**NOTE:** The test suite has not been maintained recently, so expect many
tests to fail.
%% // TH 2012-08-06

GF has testsuite. It is run with the following command:
```
$ cabal test
```
The testsuite architecture for GF is very simple but still very flexible.
GF by itself is an interpreter and could execute commands in batch mode.
This is everything that we need to organize a testsuite. The root of the 
testsuite is the testsuite/ directory. It contains subdirectories which
themself contain GF batch files (with extension .gfs). The above command
searches the subdirectories of the testsuite/ directory for files with extension
.gfs and when it finds one it is executed with the GF interpreter.
The output of the script is stored in file with extension .out and is compared
with the content of the corresponding file with extension .gold, if there is one.
If the contents are identical the command reports that the test was passed successfully.
Otherwise the test had failed.

Every time when you make some changes to GF that have to be tested, instead of
writing the commands by hand in the GF shell, add them to one .gfs file in the testsuite
and run the test. In this way you can use the same test later and we will be sure
that we will not incidentaly break your code later.

If you don't want to run the whole testsuite you can write the path to the subdirectory
in which you are interested. For example:
```
$ cabal test testsuite/compiler
```
will run only the testsuite for the compiler.