GF Developers Guide
Authors: Björn Bringert  and  Krasimir Angelov
Last update: %%date(%c)

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= Setting up your system for building GF =

Before to build GF from sources you need to install some tools on your system.
GF is written in Haskell, so first of all you need recent version of the Haskell compiler GHC.
Currently we use GHC 6.10.3 and we recommend that you should use the same version
as well. This version is not backward compatible with the previous major releases
so you cannot use previous versions. GHC is available from here:

http://www.haskell.org/ghc/

Once you have installed GHC, 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 GHC was successful you should see message like:
```
The Glorious Glasgow Haskell Compilation System, version 6.10.3
```
The other two tools that we use are the lexer generator for Haskell - Alex:
http://www.haskell.org/alex/
and the parser generator - Happy:
http://www.haskell.org/happy/.
Again after the installation check that the tools are available from the terminal.
If they are not then probably you have to update the current search path in your system.

It is also a good idea to have either readline, editline or haskeline installed.
This are libraries for user friendly command line editing. On Linux, without some of this
libraries, the command line editor is very basic. Actually the only key for editing
that you can use is backspace. On Windows you get much more user friendly editor
by default but with it you cannot use the GF specific tab completion. In any case if you
plan to use GF for continuous development then it is recomended to install
some of these libraries. The GF configuration script checks the libraries
in the following order:

- haskeline
- readline
- editline


the first that is found will be used in the compilation. The libraries are also written
in Haskell and could be found on Hackage: http://hackage.haskell.org/packages/archive/pkg-list.html. If you want to check whether,
you already have some of these you can use the following command:
```
$ ghc-pkg list
```
which shows the list of all installed libraries. 

Haskeline is the easiest to install because it is a pure Haskell library but currently
with this editor GF doesn't provide word completion. With editline we provide word completion
but the library is harder to install because it is a Haskell binding to a
library with the same name written in C. If you do not have the C library you will have to install
it first. Unfortunately editline does not have good support for Unicode. This will be a problem
if you tend to work on non-Latin language. Finaly readline supports both word completion
and Unicode. Currently this is the best supported library.

Before to get the GF sources you also need Darcs. Darcs is a decentralized revision control system, 
see: http://darcs.net/ for more information. There are precompiled packages for many platforms available at
http://darcs.net/DarcsWiki/CategoryBinaries. There is also source code if you want to compile it yourself. Darcs is
also written in Haskell and so you can use GHC to compile it.


= Getting the sources =

Once you have all tools in place you can get the GF sources. 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 sources but if
you want these changes to be applied back to the main sources you will have to send the changes to us.
If you plan to work continuously on GF then you should consider to get 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):

```
$ darcs get --partial --set-scripts-executable http://code.haskell.org/gf/
```

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


=== Updating your copy ===

To get all new patches from the main repo:
```
$ darcs pull -a
```
This can be done anywhere in your local repository, i.e. in the ``gf``
directory, or any of its subdirectories.
Without ``-a``, you can choose which patches you want to get.


=== Recording local changes ===

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:

```
$ darcs add file1 file2 ...
```

To record changes, use:

```
$ darcs record
```

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.

If you think there are too many questions about what to record, you
can use the ``-a`` flag to ``record``. Or answer ``a`` to the first
question. Both of these record all the changes you have in your local
repository.


=== 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 have a user account on code.haskell.org, you can get read-write access over SSH
to the GF repository. 
To get an account, [fill out this form http://community.haskell.org/admin/account_request.html].
Once you have an account, ask <aarne@chalmers.se> to add you to the ``GF`` project.


=== Getting a fresh copy ===

Get your copy with (all on one line),
replacing ``bringert`` with your own username on code.haskell.org:

```
$ darcs get --partial --set-scripts-executable bringert@code.haskell.org:/srv/code/gf
```

The option ``--partial`` means that you do not download all of the
history for the repository. This saves space, bandwidth and CPU time,
and most people don't need the full history of all changes in the
past.


=== Getting other people's changes? ===

Get all new patches from the main repo:

```
$ darcs pull -a
```

Without ``-a``, you can choose which patches you want to get.



=== Commit your changes ===

There are two steps to commiting a change to the main repo. First you
have to record the changes that you want to commit, then you push them
to the main repo. For instructions on recording your changes locally,
see "Recording local changes" above. Then you can push the patch(es) to 
the main repo. If you are using ssh-access, all you need to do is:

```
$ darcs push
```

If you use the ``-a`` flag to push, all local patches which are not in
the main repo are pushed.



=== Apply a patch from someone else ===

Use:

```
$ darcs apply < mypatch.patch
```

This applies the patch to your local repository. To commit it to the
main repo, use ``darcs push``.

== Further information about Darcs ==


For more info about what you can do with darcs, see http://darcs.net/manual/


= Compilation from sources =

The build system of GF is based on Cabal (see http://www.haskell.org/cabal/ for more information).
Cabal is installed by default together with the GHC compiler. This is actually a library which could
be used from Haskell to compile projects written in Haskell. The entry point is a script
called Setup.hs which is placed in the top directory of every project managed with Cabal.
The three main steps that are needed for compilation are much like what you do in a project
written in C, you have: configure, build and install.


== 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:
```
$ runghc Setup.hs configure
```
The command ```runghc``` comes with the GHC compiler and is batch interpreter which executes
the specified script without the need to compile it advance. Setup.hs is our compilation driver
which is based on Cabal. 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.

== Build ==

The build phase does two things. First it builds the GF compiler from the Haskell sources
and after that it builds the GF Resource Grammar Library using the already build compiler.
The simplest command is:
```
$ runghc Setup.hs build
```
Again you can add the option ```-v``` if you want to see more details.

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:
```
$ runghc Setup.hs 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:
```
$ runghc Setup.hs build present
```
Before to use this command make sure that the script lib/src/mkPresent has executable
permissions on Linux.

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:
```
$ runghc Setup.hs build langs=Eng,Swe
```

== Install ==

After you have compiled GF you can install the binaries to make the system usable.
On Linux you will need root privileges to do this. Use the command:
```
$ su
```
and enter the root password. This step should be skipped on Windows.

The installation itself is started with the command:
```
$ runghc Setup.hs install
```
This command installs the GF compiler in the default place for executable
files in your system. For example on Linux this is usualy /usr/local/bin and on
Windows this is c:\Program Files\Haskell\bin. If you want to install in some
other place then use the ```--prefix``` option during the configuration phase.

The compiled GF Resource Grammar Library will be installed in /usr/local/share/gf-3.0/lib
on Linux and in c:\Program Files\Haskell\gf-3.0\lib on Windows. Again the location could
be changed using the ```--prefix``` option.

== Clean ==

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

== SDist ==

You can use the command:
```
$ runghc Setup.hs sdist
```
to prepare archive with all source codes needed to compile GF.

= 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. 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
```

= Running the testsuite =

GF has testsuite. It is run with the following command:
```
$ runghc Setup.hs 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:
```
$ runghc Setup.hs test testsuite/compiler
```
will run only the testsuite for the compiler.
