[pmcjones]

> which is why it took 20 years of further research to go from Lisp 1 to Scheme.

Actually it only took Peter Landin a few years. For example see:

P. J. Landin, The Mechanical Evaluation of Expressions, The Computer Journal, Volume 6, Issue 4, January 1964, Pages 308–320, https://doi.org/10.1093/comjnl/6.4.308

[lisper]

Thanks for that link! TIL.

[pmcjones]

Also: MIT's PAL (1968 -- Art Evans, Martin Richards, and others) and John Reynolds' GEDANKEN (1969):

https://www.softwarepreservation.org/projects/PAL/

https://www.softwarepreservation.org/projects/GEDANKEN/