Not sure why you'd guess that since Lisp machines weren't a thing in the 1950s. His NLS https://en.wikipedia.org/wiki/NLS_(computer_system) https://en.wikipedia

Not sure why you'd guess that since Lisp machines weren't a thing in the 1950s. His NLS https://en.wikipedia.org/wiki/NLS_(computer_system) https://en.wikipedia.org/wiki/NLS_(computer_system) was actually written in something rather different, TREE-META https://en.wikipedia.org/wiki/TREE-META https://en.wikipedia.org/wiki/TREE-META I'm not entirely sure what you would call their programming languages, but they definitely weren't Lisps.