Do you have actual benchmarks comparing the the runtimes to justify the competitiveness between the two programs? With no types declared and no optimization declarations, I feel it would still be around 2-10x slower than C. (I have no quantitative evidence for that feeling though, except that I write Common Lisp in my day job. I have no doubt the program could be within 1-2x of C with appropriate massaging.) That’s certainly “good enough” in most cases, as evidenced by Python running so much of the world.

The blasé attitude toward adhering to POSIX/GNU wc behavior was a bit dissatisfying to me. Those additions are “trivial” and probably don’t change the shape of the program too much, but are nonetheless complicating and time-consuming factors. I would prefer that Lispers strive to complete 100% of the job, not the 80% cut that matters to them. :)

With all that said, I agree with the opinion of the article, being preferable to write Lisp over C, though I would be up-front about the meaning of “beating C”. C has been beat—in my and the author’s opinion—because Lisp strikes an unusually good balance between execution efficiency, speed of development, program safety, and expressiveness. But even better, Lisp lets you push in any of these directions, often with only modest sacrifices in the others.

However, the original spirit of the wc exercise was to make it fast, Benchmarks Game-style.