Remembering John Conway's FRACTRAN, a ridiculous, yet surprisingly deep language
Published on: 2025-05-02 23:36:24
On April 8, 2020, John Horton Conway developed symptoms of COVID-19. On April 11, 2020, he succumbed to the disease.
Like so very, very many, I mourn Conway’s passing, and yet I also celebrate his life. I celebrate his accomplishments, I celebrate his curiosity, and I celebrate his skill at making important topics in mathematics engaging and interesting.
One of the finest examples of that skill is the programming language FRACTRAN, the subject of this essay.
Prelude
John Horton Conway in 1993
Conway touched my own life from early days. As I described in The Eight Queens Problem… and Raganwald’s Unexpected Nostalgia:
My mother had sent me to a day camp for gifted kids once, and it was organized like a university. The “students” self-selected electives, and I picked one called Whodunnit. It turned out to be a half-day exercise in puzzles and games, and I was hooked.
One of the things we talked about in “Whodunnit” was Conway’s Game of Life. I don’t recall playing with it much: The
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