1993
Philip Greenspun states his tenth rule
Philip Greenspun jokes that big C programs secretly reinvent Lisp badly — the observation known as Greenspun's Tenth Rule.
Quote
“Any sufficiently complicated C or [Fortran] program contains an ad-hoc, informally-specified, bug-ridden, slow implementation of half of Common Lisp.”
What it was for
There are no rules one through nine; Greenspun picked 'tenth' for memorability. The line explains why frameworks grow interpreters, DSLs, and config languages — and why starting with a higher-level tool might have been cheaper.
People
- Philip Greenspun — author
Why it's here
The snarkiest law about accidental language design in legacy codebases.
Why it mattered
It named the pattern of reimplementing Lisp features inside lower-level systems.
What it solved
TeamsMicrosoft Teams — chat, video calls, and Office integration for workplace collaboration. building elaborate C++ frameworks lacked a humorous label for what they were doing.
Media
ImagePhilip GreenspunElsa Dorfman, CC BY-SA 3.0, via Wikimedia Commons