Yikes. I got a mental wire-crossing, and misattributed the origin of APL\11. It was Ken Thompson who wrote the version I was thinking of. Here is a link to the early history of the project:

http://sigapl.org/Archives/waterloo_archive/apl/apl-11/QL_Si...

A recent version that has gone through many iterations can be found at

https://github.com/PlanetAPL/openAPL

If you google "Ken Thompson APL\11" you will find several links, including ancient archived versions of the code.