Read Eval Print Loop

The property of Lisp, REPL, also called interactive top level, makes it a good prototyping tool. Paul Graham in "The Roots of Lisp," tells us that John McCarthy showed how, given a handful of simple operators and a notation for functions, you can build a whole programming language. He called this language Lisp, for "List Processing," because one of his key ideas was to use a simple data structure called a list for both code and data.

This concept of using a single object for both code and data, has its origin with Alan Turing, John von Neumann's student. Nevertheless McCarthy constructed something that we can use to this day, Lisp.

I found this about Turing in John von Neumann.

"During 1936 through 1938 Alan Turing was a graduate student in the Department of Mathematics at Princeton and did his dissertation under Alonzo Church. Von Neumann invited Turing to stay on at the Institute as his assistant but he preferred to return to Cambridge; a year later Turing was involved in war work at Bletchley Park. This visit occurred shortly after Turing's publication of his 1934 paper "On Computable Numbers with an Application to the Entscheidungs-problem" which involved the concepts of logical design and the universal machine. It must be concluded that von Neumann knew of Turing's ideas, though whether he applied them to the design of the IAS Machine ten years later is questionable"