Vala - Compiler for the GObject type system

Introduction

Vala is a new programming language that aims to bring modern programming language features to GNOME developers without imposing any additional runtime requirements and without using a different ABI compared to applications and libraries written in C.

News

• May 12, 2008: Vala 0.3.2 released

• April 21, 2008: Vala 0.3.1 released

• April 7, 2008: Vala 0.2.0 released

• March 2, 2008: Vala 0.1.7 released

• January 19, 2008: Vala 0.1.6 released

valac, the Vala compiler, is a self-hosting compiler that translates Vala source code into C source and header files. It uses the GObject type system to create classes and interfaces declared in the Vala source code. It's also planned to generate GIDL files when GObjectIntrospection is ready.

The syntax of Vala is similar to C#, modified to better fit the GObject type system. Vala supports modern language features as the following:

• Interfaces
• Properties
• Signals
• Foreach
• Lambda expressions
• Type inference for local variables
• Generics
• Non-null types

• Assisted memory management

• Exception handling

• Type modules (Plugins)

Vala is designed to allow access to existing C libraries, especially GObject-based libraries, without the need for runtime bindings. Each to be used library requires a Vala API file at compile-time, containing the class and method declarations in Vala syntax. Vala currently comes with experimental bindings for GLib and GTK+. It's planned to provide generated bindings for the full GNOME Platform at a later stage.

Using classes and methods written in Vala from an application written in C is not difficult. The Vala library only has to install the generated header files and C applications may then access the GObject-based API of the Vala library as usual. It should also be easily possible to write a bindings generator for access to Vala libraries from applications written in e.g. C# as the Vala parser is written as a library, so that all compile-time information is available when generating a binding.

Why Vala?

Many developers want to write GNOME applications and libraries in high-level programming languages but can't or don't want to use C# or Java for various reasons, so they are stuck with C without syntax support for the GObject type system. The Vala compiler allows developers to write complex object-oriented code rapidly while maintaining a standard C API and ABI and keeping the memory requirements low.

C# and Java libraries can't be used the same way as native GObject libraries from C and other languages and can't be accepted as part of the GNOME Platform. Managed applications also suffer from usually higher memory requirements which is not acceptable in some situations.

valac produces C source and header files from Vala source files as if you've written your library or application directly in C. Using a Vala library from a C application won't look different than using any other GObject-based library. There won't be a vala runtime library and applications can distribute the generated C code with their tarballs, so there are no additional run- or build-time dependencies for users.

Current Status

The Vala compiler is self-hosting since the end of May 2006. It is capable of compiling small and large Vala applications using Gtk+ and other libraries. There is still a lot to do, though, to complete the compiler: we need to implement more semantic checks and fix more bugs as we find them. You're encouraged to test it out and provide feedback about the language or the compiler.

• Roadmap to Vala 1.0

Tool Support

• Autotools support is under development. Progress is tracked with Bug 472048. Would be nice if some Perl/Automake guru would merge the vala-support script into the automake script.

• Emacs mode available.

• Vim configuration

License

The Vala compiler is licensed under the LGPL 2.1+

Documentation

We're still working on documenting the whole language. The current draft can be found at http://www.vala-project.org/doc/vala/

Bindings Documentation

Hackers' Guide to Vala

Tutorial

If you want some tips before start hacking in Vala, take a tutorial and see what you can do with this, ;D

It's still under heavy development, so take it easy.

• The Vala tutorial (Draft)

Sample Code

• Basic Sample

• List Sample

• Advanced Sample

• Properties Sample

• GTK+ Samples

• Cairo Sample

• Plugins

• DBus Sample

• DBus Server Sample

• GStreamer Sample

• BlueZ DBus Sample

• Hildon Sample

• Input Sample

• Glade Sample

• Poppler Sample (PDF Viewer).

• Sqlite Sample

• Lua Sample

• Async GIO Sample

• Gnome-Desktop and GMenu Sample

• Panel Applet Sample

• Xml Sample

• Implementing Vala interfaces in C

Applications developed in Vala

• Scratchpad Spatial text editor for the GNOME desktop

• Paldo Installer Installer for the Paldo Linux Distro

• OpenMoko Terminal

• People Project aims at providing an unified access to contacts for desktop applications

• Vala Benchmarks

• radare Multi-architecture assembly code graph in Vala-Cairo

• Abraca A GTK+ XMMS audio player

• Shishen Sho Mahjongg

• GNOME Scan, mixed with C/GObject.

• Cheese, a branch to see if cheese can be implemented in vala

Download

Releases can be found on /Release

Development is going on http://svn.gnome.org/svn/vala/trunk and can be viewed here.

You can check out the current development snapshot using (please note, that you need vala installed to build it from svn):

 svn co http://svn.gnome.org/svn/vala/trunk vala

Requirements

• GLib 2.12 or later

Contact

There is a mailing list for developer and general discussions. There is also an IRC channel #vala on GIMPnet. Bugs can be reported in Vala bugzilla page.

• Jürg Billeter <j at bitron dot ch>

• Raffaele Sandrini <rasa at gmx dot ch>