June 2009
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Building Linguistic Structure

Yesterday, I had an interesting thought. My advisor once made the cultural observation that many people in Computer Science invent their own language and then immediately write a self-hosting compiler. I agree that a compiler is quite a feat of engineering and serves as a nice test case to demonstrate that the language you’ve invented is powerful enough that it can handle real-world complexity. Unfortunately, this test fails in a few important ways.

First, It doesn’t actually show as much as you think it might. There is a very strong filter on failed languages. By using this test the author runs the risk of re-designing the language, specifically to insert constructs that help them build the compiler. Now, this isn’t necessarily a bad thing, except that compiler writing is now a fairly mature field. There are standard abstractions (esp. in the lexing and parsing) that a new language will probably not experiment with. So, the author will usually just build these existing and well-understood abstractions into the new language. Rather than encouraging language experimentation we get more of the same, but with different syntax.

Second, Not all useful languages even have their own compiler. I’m specifically thinking of the domain specific languages (DSL). Nobody would write an awk interpreter in awk; or a mail engine using sendmail (even if it is Turing Complete). These are languages designed to do a specific task, many of them are quite essential to their respective fields, but none of them are self-hosting. Nor should we expect them to be.

My argument here is that the cultural practice of writing a self-hosting compiler is a big distraction. New languages should be for experimenting with new linguistic constructs. We should be looking toward the DSLs, and incorporating their innovations into our more main-stream languages. Right now, we seem to be optimizing our languages for compiler construction.

I’d rather see our languages evolve in a different direction. I’m really eager to witness the birth of an AI. For this to happen though, we need languages for expressing patterns of thought, not patterns of bits. We need the ability to cohesively and flexibly assemble the stuff of thought. I’m thinking Society of Mind stuff here. We need languages that allow for statistical fuzziness, sloppy associativity, and the ability to construct metaphor.

The linguistic tools that we find useful for building compilers are not necessarily the same tools that will help us build a mind.

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