Wow, I had no idea "Mr. CP/M" was into APL...
The list of people who implemented (Quasi-)APLs contains some further illustrious names:
- Ken Thompson (APL\11): https://groups.google.com/forum/#!topic/comp.lang.apl/u9sl6g...
- Dan Bricklin (Multics APL): http://lowendmac.com/2006/dan-bricklin-inventor-of-the-elect...
- Bill Gates (designed, never published): http://americanhistory.si.edu/comphist/gates.htm#tc30
- Robert Griesemer: https://en.wikibooks.org/wiki/Go_From_Scratch/The_Origin_of_...
- Rob Pike: https://github.com/robpike/ivy