Also important to note is that J is the final language from the inventor of APL (Ken Iverson) who also got the Turing award for APL. J has some advancements from vanilla APL & doesn't require a special keyboard or symbols. Some of these new features were added to Dyalog APL (modern APL with good support). Roger Hui is a well known figure in the APL community. He helped write J and works for Dyalog APL now.
.... and the J implementation is inspired by the "A" miniature APL interpreter written by Arthur Whitney who later went to create K. See http://code.jsoftware.com/wiki/Essays/Incunabulum for more (and google "J incunabulum" if you want to see other people's commentaries)
