"The final impetus that got J started was the one-page interpreter fragment that Arthur wrote, recorded in Appendix A of An Implementation of J [29] and also reproduced in Appendix A below. My immediate reaction on seeing the page was recoil and puzzlement: it looked nothing like any C code I had ever seen. (“Is it even C?”) However, Ken counselled that I should reserve judgment. "
http://queue.acm.org/detail.cfm?id=1531242
It turns out he rewrites the whole compiler from scratch in C every four years.
This is a snapshot from the source code of 'J' also by Arthur Whitney - the precursor to 'K'.
http://keiapl.org/rhui/remember.htm#incunabulum
This is it described by Ken Iverson:
"The final impetus that got J started was the one-page interpreter fragment that Arthur wrote, recorded in Appendix A of An Implementation of J [29] and also reproduced in Appendix A below. My immediate reaction on seeing the page was recoil and puzzlement: it looked nothing like any C code I had ever seen. (“Is it even C?”) However, Ken counselled that I should reserve judgment. "
http://keiapl.org/rhui/remember.htm