Forth ? 
  * http://galileo.phys.virginia.edu/classes/551.jvn.fall01/primer.htm
  * http://wiki.laptop.org/go/Forth_Lessons
  * https://skilldrick.github.io/easyforth/
  * Forth for education http://4e4th.eu/ && https://www.complang.tuwien.ac.at/anton/euroforth/ef12/papers/bruehl.pdf
  * https://yosefk.com/blog/my-history-with-forth-stack-machines.html
  * Itw with Charles Moore (MIT 1961') https://youtu.be/Qq0d6k7oi_A

POSTFIX ARITHMETIC

''3 4 + .'' 

-> ''7''

STACK

'' : clone dup .s ;''

''1 clone''

-> ''1 1 ''

==== Forth on a chip ====

ESP8266 https://github.com/zeroflag/punyforth