Greenspun's tenth rule
Greenspun's tenth rule of programming is an aphorism in computer programming and especially programming language circles that states: Any sufficiently complicated C or Fortran program contains an ad hoc, informally-specified, bug-ridden, slow implementation of half of Common Lisp. == Overview == The rule expresses the opinion that the argued flexibility and extensibility designed into the programming language Lisp includes all functionality that is theoretically needed to write any complex computer program, and that the features required to develop and manage such complexity in other programming languages are equivalent to some subset of the methods used in Lisp.