The Roots of Lisp

paulgraham.com

Technology

2 min read → 35 sec

A short essay on John McCarthy's 1960 discovery that a programming language can be built from a small core, and why Lisp's self-describing design has shaped later language development.

John McCarthy showed in 1960 that a whole language can be built from a few simple operators.

Lisp's defining quality is that it can be written in itself.

McCarthy's 1960 paper did for programming something like what Euclid did for geometry.

Lisp means "List Processing."

Lisp uses lists for both code and data.

Lisp has a semantic core, which is why it has dialects unlike other languages.

Lisp's defining quality is that it can be written in itself.

Programming has had two clean models so far, the C model and the Lisp model.

The C model and the Lisp model are points of high ground, with swampy lowlands between them.

A common recipe in the past 20 years was to start with the C model and add Lisp features piecemeal.

Understanding McCarthy's result helps explain where programming languages are heading.

Retracing McCarthy's steps in running Common Lisp code shows what he discovered in simple terms.