Argh! Tutorial Part 0

This is a prequel to part 1 of the Argh! tutorial series. As it turns out hacking Argh! code is much more fun, when you are able to actually run it.

So in this part I’ll show you how to get your Argh! interpreter¹ up and running.

For the Lazy Folks: JS Argh!

There is an implementation of Argh! in javascript which can be run directly in your browser. Go straight to http://argh.sha-bang.de/ an give it a try! As all officially endorsed Argh! interpreters JS Argh! is Free Software, you can get the source from the mercurial repository at: http://hg.intevation.org/argh/js.

The official Argh! distribution

If the JS Argh! implementation gets to tedious and slow you want an real native Argh! interpreter on your system. The canonical source of Argh! interpreters is the official Argh! distribution, which contains various implementations of the Argh! in different languages, Argh! example code and some programming tools, like Argh! modes for GNU Emacs and Vim and more…

There are various ways of getting the official Argh! distribution:

1. You can download the latest release:
   http://sha-bang.de/12_eso/argh-0.2.3.tgz
   The releases tend to be rather outdated (which means: extremely outdated, and therefor incomplete) — but the reference Argh! interpreter included in the archive is stable and usable.

2. You can clone the latest version from the official mercurial repository:
   hg clone http://hg.intevation.de/argh/
   This is the best way to be always up to date with Argh!.

3. Finally, if you don’t want to use mercurial, you can download a current snapshot of the repository:
   http://hg.intevation.de/argh/archive/tip.tar.gz

I strongly recommend to go with the current repository, by using method 2 or 3.

Building the reference interpreter

After getting the Argh! distribution one way or the other, you have to build the interpreter. I’ll assume you are using a GNU/Linux system and that you have at least make and gcc installed. On other *nix like systems building should work the same (feel free to report problems. If you are using Windows, you are on your own…

To build the default reference interpreter enter the directory with the Argh! distribution and type make:

$ hg clone http://hg.intevation.de/argh/
$ cd argh
$ make

that will create a sub directory bin with the interpreter binaries argh and aargh. Now you can use the interpreters by calling them with the Argh! source to interpret:

$ ./bin/argh examples/hello.agh
Hello World

Or in case of Aargh! programs:

$ ./bin/aargh examples/pi.agh
3.141592653589793238462643383279

Additional implementations

the sub directory argh contains the various implementations. There are implementations in various languages, from ADA to rpython… argh/c contains an implementation in ANSI C, which happens to be the reference interpreter we just build. The text file argh/README contains a complete list, including authors and licensing information.

Worth mentioning are especially:

• argh/erlang by Bernhard Herzog, written in erlang this was the first and original Aarrgh! interpreter, that is Aargh! with additional support for concurrency in Argh! programs.

• argh/go by Sascha Teichmann, written in go this is a complete A(a)r(r)gh! implementation, that is: all dialects are supported and can be selected separately. Especially noteworthy is, that the go implementations are trying hard to optimize the execution of Argh! code and therefore are much faster than the other implementations with some A(a)rgh! programs. This especially true for large, generated Argh! programs.²

More to explore

As mentioned before the Argh! distribution does contain more than interpreters: The example sub directory contains various Argh! examples, from the simple Hello World to calculation of Fibonacci numbers and Pi.

The tools sub directory contains utilities for the Argh! hacker: Vim and Emacs programming modes, where the Emacs mode includes an complete A(a)rgh! interpreter and debugger. And tools/bf2aargh which is an BrainFuck to Aargh! compiler written in Python.

So, now that you have everything you’ll need: Happy Argh! hacking!