Saturday, December 1, 2012

Rapid Programming Language Prototypes with Ruby & Racc, Commentary

I just watched a tolerable ruby conference video by Tom Lee on Rapid Programming Language Prototypes with Ruby & Racc.

What he showed he showed fairly well. His decision to "introduce compiler theory" was, he admitted, last-minute and the hesitation in its delivery bore testimony to that. The demonstration of the compiler pipeline using his intended tools (ruby and racc) was done quite well with a natural progression through the dependent concepts along the way. By the end of the talk he has a functional compiler construction tool chain going from EBNF-ish grammar through to generated (and using gcc, compiled) C code.

I was surprised that nobody in the audience asked the question I was burning to ask from half way through the live-coding session: Why not use Treetop? (or the more generic: why not use a peg parser generator or a parser generator that does more of the heavy lifting for you?)

The whole point of Tom's presentation is: use ruby+racc because it saves you from all the headaches of setting up the equivalent tool chain in C/C++. And it does, he's right. But it feels to me that Treetop does even more of that hard work for you, allowing you to more quickly get to the fun part of actually building your new language. I'm angling for simplicity here.

I could be wrong, though, so let me ask it here (as Confreaks seems to not allow comments): Why not treetop (or an equally 'simple' parser generator) for something like this? (and answers along the lines of EBNF > PEG are not really what I'm after, but if you have a concrete example of that I'd like to hear it too.)

On a completely separate note: Tom, you need to add some flying love to your Vim habits. :-)