Yet another Kernel interpreter

I wrote another Kernel-ish interpreter in JavaScript: Virtua.

This time, no tail-call optimization or first-class continuations, just plain old pedestrian control flow: LOOP, CATCH, THROW, UNWIND-PROTECT (unexpectedly, this didn't make the interpreter much smaller than the one with TCO and continuations.)

Probably the only interesting thing in there is that everything is fully OOP: EVAL is a message, as is COMBINE, as is MATCH - which means every object can potentially control its own evaluation, act as a combiner, and be used as a left-hand-side pattern in matching.

Again: Kernel is nice and elegant, but the interpretetive overhead of fexprs is killer [Edit: haven't measured it, and see this]. Maybe it doesn't matter for what I want to do: script web GUIs.

Previously: The Kernel Underground.

Algebraic Data Types

Reading this incredibly insightful article The Algebra of Data, and the Calculus of Mutation finally drove home the point to me why FP folks are so in love with their Algebraic Data Types: they connect wonderfully with very old (think B.C.) mathematical ideas - that every one of us has learned in school. The question is still whether that does make them good for programming. (HT Daniel)