A Lexical Mistake

Like many gamedev enthusiasts, I’ve only finished a handful of computer games and, perhaps not surprisingly, most of those were never released even on my homepage either. Usually the point of game development at an enthusiast or hobbyist level is not to create gaming masterpieces anyway, but rather to simply learn about the process and have fun working the code (or graphics, design, et cetera), and maybe even develop a few reasonably simple games.

Over the years I’ve spend quite a bit of time learning the gamedev concepts and recently I was able to apply some of them in a project, intended to test Haskell’s gamedev capabilities for hobbyist or small team game development (related post). Specifically I was interested to see how the difference between Haskell and Object-Oriented languages changed the design and implementation of the game code and engine, hopefully lending itself to the eventual development of languages tailored towards game development.

I set out to develop one of my favorite arcade remakes–yet another variation of Geometry Wars. The premise would be to keep the game as simple as possible, only the basic gameplay would be present with a couple of levels of progression. Enough to test all of the simple elements of gameplay ready for a more substantial project. As you may have guessed from the absence of the obligatory screenshot it didn’t work out as well as I expected.

Luckily I did pick up a couple of things while working on the game, and better yet I may even be able to rewrite the code and find that screenshot yet. It all comes down to a couple of quirks in Haskell’s syntax which didn’t blend well with my usual game architecture. Obviously the architecture would need to be modified to suite the idiomatic style of Haskell, but I was reasonably certain (and still are) that the architecture is the simplest implementation for both Object-Oriented languages as well as functional languages, based almost solely on the requirements of the high level game data structures.

The Haskell code for these structures was essentially based directly on records. The records originally contained only functional values, but I quickly realized how crazy that was, which lead me to the current design which uses records full of IORefs, at least for the mutable slots. (If its not immediately obvious why the IORefs are needed, it might help to know that game objects quite often need to reference each other simply because the operations are related between the two…bullets from the player ship for example.)

Finally, after working with this approach for a while it eventually sunk in that I could probably write the same code in Python in not only half the time, but also quicker for the same number of overall bugs. Not because the bugs are easier to catch in Python…they really, really aren’t. But because Python allows me to test many more variations of the game. At least more variations than Haskell seems to, all of which makes me wonder if I haven’t quite tapped into the idiomatic code still.

So I’m not quite out of ideas yet. I believe I can tweak my accessors to reduce the namespace damage caused by them (at the expense of some verbosity, however…why the hell hasn’t this been fixed yet anyway). And there’s even some clever usage of typeclasses which could simplify the use of common algorithms between game objects. If all goes to plan I’ll have some code to post next time…

– Lorenz

Theres been quite a lot of work going into the blog under the surface recently. The most important being an update to the current version of…well everything. The most obvious ramification of this process have been the change in theme, back to the default bundled theme (not counting the header color which is modifiable in the settings page of the them). I intend to keep this version which is considerably faster (than K2) and I think still more than usable, while I start developing a completely new theme for the blog (no time frame however, as per usual).

The other change is not particularly obvious, but basically the site is now under the Git DVCS. This will make it significantly simpler to manage any updates of the site while concurrently maintaining the code I write for the plugins and visual style. Basically the site is maintained through a collections of branches which are rebased into the deployed branch which is finally published to the server. The files on the server are then reset to the latest version of the deployed branch. The side affect of this being, I can update any single piece using its corresponding feature branch and simply rebase the dependent branches to the last patch on that branch, while any changes after the branch or merge point are simply re-applied afterwards (by Git, not me). Update…fix conflicts…push…done!

So I promised more actual posts I believe, I am getting to it, albeit slowly.

For some background into the lack of actual language related work I’ve produced lately it helps to understand, arguably the most important, project that I’m working on right now. The Mention Programming Language is a new language that I’ve had in the works since the very beginning of this blog. At one point I even had some pages dedicated to the language. Don’t bother looking, there are no posts about the language yet… I decided very early on to develop the language in the dark, at least until I was sure that it would lead to an actual release of some sort (I’ve worked on quite a few dead language designs over the years).

So Mention is a functional programming language with strong influences from Haskell, and Smalltalk. Yup, you heard right, the design of the language is a dynamic one, which despite the Haskell based syntax will provide a myriad of dynamic features like delegation and accessors more, much more reminiscent of Smalltalk than Haskell. There are a couple of other minor influences that creep in there every so often, due to other languages I’ve worked with or investigated (the design), but those are the main ones.

There’s only one problem, however. I don’t understand the math (lambda calculus and type theory) needed to implement the language yet. I’m getting there but it is taking a little while. The good news is that this wont stop me from posting for much longer. Some of the posts might be about specific things relating the the theory, but the real problem was my lack of a mathematical background. Thanks to my undergrad math text that problem is much less of an issue now and it the Mention project should be getting underway properly very soon, expect some posts on the non-implementation issues like the syntax high level semantics.

On another issue might now be obvious why I haven’t finished the Scheme parsing library and the corresponding series about its design and implementation… I’m not working in Scheme anymore. There is still plenty I could say about the design of Scheme and Lisp dialects, but I’ll leave that for later, but what I would like to add in post in the near future is the relationship between laziness + monads and strictness + mutable-state. For this comparison I’ll be using Scheme and Haskell (don’t worry…the code will only be for examples in both cases). What won’t be happening is any more posts or work on the Scheme parser itself.

– Lorenz

After sitting on the domain name associated with my online handle (Krysole), I’ve finally decided it was time to move my blog to an URL using its own namesake.

What does this mean?

From now on the proper URL for A Lexical mistake is simply alexicalmistake.com

The configuration for the site seems to properly redirect pretty much everything to the new URL (including permalinks… I’ll keep the old URL pointing to the site for this very reason).

On another issue, the blog very much isn’t dead, it just seems that way because I’ve been somewhat preoccupied lately. The main reason for this is my move to Linux, or more specifically Ubuntu. I’ve also been transitioning most of my mac dependencies to their web equivalents (Google reader, etc).

The point is I should be back to posting biweekly again (or close too), very soon now.

– Lorenz