Erlang Text Elite

This last weekend, I somehow came to think about the wonderful old space trading game Elite, and the way it managed to cram a vast universe of planets with names, stats, and fun descriptions (along with the 3D space flight simulation, which was an amazing feat in itself) into the tiny 8-bit home computers of old. Only minutes later, I had found Ian Bell's Text Elite web page, where Ian, one of the two original authors of the game, has published a reconstruction in C of the main universe-generating algorithm, along with a simple text interface to actually let you "play", i.e., buy, sell, and jump between planets. Great!

So I rewrote it in Erlang. And had a lot of fun doing it. Apart from the nostalgic kick, there were two points with the exercise: First of all, I just wanted to see the main algorithm as cleanly implemented as possible. But second, I wanted to see what it would be like to rewrite a piece of classic game code that was very clearly not written with functional programming in mind (though of course already cleaned up a bit by being rewritten in C from the original 6502 assembler). I think I like how the result turned out; it's quite clean and readable, and the data flows are easy to follow. I also found and fixed a bug in the "goat soup" function.

The code can be found on GitHub, along with the two scripts for testing found on Ian's page. You can run them like this:
erl -noshell -s txtelite main -s init stop < sinclair.txt
(To play yourself, just skip the last "< sinclair.txt" part.) Of course, you need to compile the txtelite.erl file first. If you're new to Erlang, this is how:
erlc txtelite.erl
It's good to be back on Lave again!

Comments

Post a Comment

Popular posts from this blog

The Hobbit (1982 game) graphics engine in Javascript

Tunnel like hall Great river Trolls' path Narrow place Dragon's desolation Straight smooth passage Dale valley Trolls' cave Forest gate Lake town Goblins' dungeon Dark dungeon Trolls' clearing Elvish clearing Lonelands Elvenking's cellar Goblins' big cavern Gloomy bewitched place Running river Lower halls Spider place Front gate One of the first computer games that really fascinated me was the 1982 text adventure based on The Hobbit, for the ZX Spectrum. I was 12 years old when I first played it, and it was immediately clear that this was different from any other game I'd seen. It was a text adventure, but some locations had illustrations in brightly coloured graphics, which although crude by today's standards really helped transport you to another world back in those days of mostly monochrome screens and text-only adventure games. There is much more to be said about what made the game so special - in fact, the graphics ...
Read more

Recreated ZX Spectrum (Bluetooth Keyboard)

Image
(Originally posted on Google+, Sep 30 2015.) So I got myself what has to be the nerdiest bluetooth keyboard in the world: http://sinclair.recreatedzxspectrum.com/ Quite expensive too, for a bluetooth keyboard. But build-wise, it's a perfect replica of the ZX Spectrum we know and love. Feels exactly right and has the correct key labels. Which means that used with a decent emulator, it recreates the feeling of typing on a real Speccy (without resorting to blind hunt-and-peck which is generally the case if you use a PC keyboard). And after some fiddling with figuring out how to unlock the full bluetooth QWERTY mode as well as the Speccy-specific mapping, I can confirm that it works as advertised as a generic keyboard for Android, iOS or Windows. I only had to ask myself, "can I think of anyone who's a more suitable target for this product" to realize that I really had to get it. It's certainly not for fast touch typing, but programming on a Speccy was more ...
Read more

The times they are a-changin'

Recently I got a call from my dad, who was having some problems with his computer, along the lines of "there's something wrong with the damn internet again". Since I was the one who set it up for him, I don't mind fixing problems when they occur, but I find that the hardest thing with these debugging sessions over the phone is to get him to quote the exact messages he is seeing. It's kind of interesting, as if the words and concepts are so alien to him that he zones out after only a second, and is actually unable to read them aloud. A typical exchange goes like this: -So, dad, what does the error message say? -Oh, something about the Internet. -OK, but what does the text say, precisely? -I dunno, Microsoft and Internet something. -Dad, can you please tell me exactly what the text says? -I just told you, it says it can't find the Internet. -Where is the message, I mean, what program does it come from? -Well, dammit, it's right here, on the screen! And so on...
Read more