Using LLMs to chat with books and documents? That's so 1978.
In the 1970s the HELPSYS facility of Interlisp-10 let you interrogate the 700+ pages Interlisp Reference Manual via an English like syntax. You could run queries on topics and system functions such as TELL ME ABOUT EVAL or TELL ME ABOUT THE 2ND ARG OF CHANGEPROP and HELPSYS would print the relevant information or section of the manual. Here's an example session from the 1978 edition of the manual:
https://www.softwarepreservation.org/projects/LISP/interlisp/Interlisp-Oct_1978.pdf#page=474
Interlisp-10 was the Interlisp implementation for the PDP-10.
