Warren Teitelman developed the Programmer's Assistant, i.e. the expression and command history and replay, undo, and editing facility of the Interlisp Exec (REPL), while working on the predecessor of Interlisp, BBN Lisp. This 1972 paper provided an overview of the early facility. https://dl.acm.org/doi/pdf/10.1145/1480083.1480119 https://dl.acm.org/doi/abs/10.1145/1480083.1480119 #interlisp #lisp #retrocomputing