The LISP 1.5 manual would help in such a task: http://www.softwarepreservation.org/projects/LISP/book/LISP%...

It's fun to write an interpretor for a lisp in Common Lisp. The book Lisp in Small Pieces goes through this.

I actually thought about writing a tutorial on how to write a complete "classic" LISP implementation. I know there are already hundreds of toy LISP tutorials but having LISP 1.5 as a goal and implementing it in much the same way it was implemented originally isn't something I've seen yet.

Magnus Myreen leveraged that property when mathematically verifying one down to machine code. Used LISP 1.5. Built a bigger language (CakeML) on that.

http://www.cl.cam.ac.uk/~mom22/tphols09-lisp.pdf

Note: Even if not doing formal methods, one can benefit from such work by making their interpreter equivalent in features, running the same tests/apps through both, and checking for their equivalence.

Doing this (for Scheme, but same concept) was the start of my programming languages class.

Or even a very dumb compiler.