Peter Landin: a computer scientist who inspired a generation

Abstract

This is the obituary of Peter John Landin, academic and gay campaigner: born 5th June 1930; an obituary 3rd June 2009. He was an outstanding thinker who set the direction of computer science for his generation. In an astonishing burst of creativity in the 1950s and 60s he showed that programs could be defined in terms of mathematical functions, how to translate them into functional expressions in the lambda calculus and how to calculate their meaning with an abstract mathematical machine, prefiguring many of the advances of the next couple of decades. Although later he turned away from computer science towards gay politics, he remained an original and extreme thinker, a complex and intriguing character.