I wrote a lot of APL for my undergraduate Senior Project in 1978/1979.

I really enjoyed it because it was fun. You could do an incredible amount of work in a single line of code.

The only problem was, that line would then be almost impossible to read and understand! It could easily be used as a "write-only" language even without a separate obfuscation step.

When I become a professional programmer right after college, I never used it again, and learned to write code that was readable above all else.

Is this an instance of the maxim that one has to be twice as smart to debug code as to write it?

Are you aware of any APL programs written using Literate Programming?

Apparently there was at least one attempt:

Lee J. Dickey. Literate programming in APL and APLWEB. APL Quote Quad, 23(4):11–??, June 1, 1993. CODEN APLQD9. ISSN 0163-6006.

Perhaps that additional layer of documentation would help? (APL is a language I've always been fascinated by, but never had occasion to more than superficially examine)