I started using Gosling’s Emacs around 1981-1982. "make" in Emacs was a game
changer!
I recall that in the Emacs documentation Gosling wrote something like, "The only
similarity between MockLisp and Lisp is the syntax." I didn’t get it--MockLisp sure
seemed like Lisp to me! Years later I did get it and viewed that as a measure of my coming
along as a computer scientist.
A couple of years later I did a project where I dropped in the Icon programming language
as a peer of MLisp (UniPress’s name for MockLisp, I believe.) See
https://www2.cs.arizona.edu/~whm/An_Icon_Subsystem_for_UNIX_Emacs_tr84_8.pdf