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A week or so ago, I did a talk on esoteric programming languages for the Twin Cities Languages User Group. One of the languages that I dived into was Befunge, a language that is quite devilish. Take a look at this program:
v > .v
3
>#v?4.@
12
>> .^
It randomly prints a number from 1 to 4 and then quits. Obvious, right? Just keep this in mind: follow the arrows, “?” randomly changes your direction, “#” is a trampoline instruction, a period prints what’s on the stack, and “@” means “quit”.
Anyway, I got to talking with some attendees and it seemed like a fair amount of attendees found Befunge to be quite interesting (probably from an insanity standpoint, but never mind that detail :) ). The more I thought about it, the more I wondered…just how hard would it be to write a compiler and/or interpreter written in .NET for Befunge … like IronBefunge? I’ve had some free time lately so I dove in to see what I could come up with.
Well, it’s not easy. Part of the reason is that the “specs” for the language (both Befunge-93 and Befunge-98) are not as complete as I’d like. There’s good information for sure, but there are some ambiguities (e.g. if an instruction expects a certain amount of values to be on the stack but the stack doesn’t have that many … you should just magically pop enough values on the stack for the operation to work). All that said, I do have a minimally working interpreter (i.e. it’ll run the random number generator program above along with standard “Hello World” programs). I’d like to have the code available, but as of the time I originally posted this article, CodePlex’s TFS was offline. Keep checking the IronBefunge site - once I can get my code up there you can check out the 0.1 version. The code is pretty messy right now - I need to do a lot of refactorings and cleanups, add support for more instructions, up the code coverage numbers (which are currently at 66%) and add some execution dump information for debugging purposes - but it’s been fun to get it up to this point. Enjoy!
Published: 07.16.2009 02:58:48 PM CST