History of Interlisp

I was first introduced to Lisp in 1962 as a first year graduate student at M.I.T. in a class taught by James Slagle. Having programmed in Fortran and assembly, I was impressed with Lisp's elegance. In particular, Lisp enabled expressing recursion in a manner that was so simple that many first time observers would ask the question, "Where does the program do the work?" (Answer - between the parentheses!) Lisp also provided the ability to manipulate programs, since Lisp programs were themselves data (S-expressions) the same as other list structures used to represent program data. This made Lisp an ideal language for writing programs that themselves constructed programs or proved things about programs. Since I was at M.I.T. to study Artificial Intelligence, program writing programs was something that interested me greatly.