APL was created by Kenneth Iverson (array based programming language still in use today in production at places like Volvo and sold by Dyalog APL) and Arthur Whitney (APL genius) made several APL like languages for banking/financial analysis applications in the late 80's in 90's to make super efficient stock ticker analysis apps. He funded kxsystems which is a very very fast memory mapped database technology that uses the "K" language which is like APL, but uses ASCII instead of Unicode glyphs. He made zillions of dollars then left again to make another company (Shakti) which uses a new version of his language. He writes a new one from scratch every few years. The "K" executable is tiny (something like a few dozen pages of C written in an extremely unusual style).
This guy explains it well although is a little zealous:
https://scottlocklin.wordpress.com/2013/07/28/ruins-of-forgo...