Lambda the Ultimate

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HTML isn’t unusual. Documents are hard to design, and general frameworks for families of documents are even harder. The conventional wisdom back in the day was that to get yourself a good DTD designed, you were looking at several tens of thousands of dollars.

Then, once you’ve got your language designed, you start the hard work on the software. Frameworks like XSLT help, but no significant language comes without a significant cost in software design.

As I've often said here ("here" in the general sense that is), XML vocabulary design is language design. Language design is hard. Hard things often cost.

However, Tim wants us to believe that one language is enough. I really hope he is wrong about that...

Neel mentioned this paper when I complained on LtU1 that I haven't seen something interesting enough to post for a while.

It is indeed an interesting, well written, paper.

The authors show the design of Program Trace Query Language (PTQL), a declarative language for querying program behaviour. The PTQL compiler can then be used to instrument a java bytecodes and insert the required data capture operations.

Quite a lot of effot went into making the instrumented code efficient enough to allow queries to be evaluated while the program is running.