Re: REPLs
"Note that this was in 1960 on an IBM 704. Contrary to what someone posted upthread, the first interactive LISP was not the 1963 PDP-1 LISP."
McCarthy's own History of Lisp paper that you cite says "L. Peter Deutsch implemented the first interactive LISP on the PDP-1 computer in 1963". McCarthy had already hacked up a proof-of concept demo on the IBM 704, but it wasn't usable system. There's some more about it at https://www.quora.com/What-was-it-like-to-use-LISP-on-an-IBM-704
