| Christopher Strachey | |
|---|---|
| Born | 16 November 1916 Hampstead, England |
| Died | 18 May 1975 Oxford, England |
| Residence | UK |
| Citizenship | UK |
| Fields | Computer Science |
| Institutions | University of Cambridge, University of Oxford |
| Alma mater | King's College, Cambridge |
| Known for | CPL, denotational semantics, Fundamental Concepts in Programming Languages |
Christopher Strachey (1916–1975) was a British computer scientist.[1][2][3] He was one of the founders of denotational semantics, and a pioneer in programming language design. He was a member of the Strachey family prominent in government, arts, administration and academia.
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Christopher Strachey was born on 16 November 1916 to Oliver Strachey and Rachel (Ray) Costelloe in Hampstead, England. Oliver Strachey was the son of Richard Strachey and the great grandson of Sir Henry Strachey, 1st Baronet. In 1919 the family moved to 51 Gordon Square. The Stracheys belonged to the Bloomsbury Group whose members included Virginia Woolf, John Maynard Keynes and Christopher's uncle Lytton Strachey. At 13, Christopher went to Gresham's School, Holt where he showed signs of brilliance but in general performed poorly. He was admitted to King's College, Cambridge in 1935 where he continued to neglect his studies. Strachey studied mathematics and then transferred to physics. At the end of his third year at Cambridge, Strachey suffered a nervous breakdown, possibly related to coming to terms with his homosexuality. He returned to Cambridge but managed only a "lower second" in the Natural Sciences Tripos.[4]
Unable to continue his education, Christopher joined Standard Telephone & Cables Ltd (STC) as a research physicist. His first job was providing mathematical analysis for the design of electron tubes used in radar. The complexity of the calculations required the use of a differential analyzer. This initial experience with a computing machine sparked Strachey's interest and he began to research the topic. An application for a research degree at Cambridge was rejected and Strachey continued to work at STC throughout the Second World War. After the war he fulfilled a long-standing ambition by becoming a schoolmaster at St Edmund's School, Canterbury, teaching mathematics and physics. Three years later he was able to move to the more prestigious Harrow School in 1949, where he stayed for three years.
In January 1951, a friend introduced him to Mike Woodger of the National Physical Laboratory (NPL). The lab had successfully built a reduced version of Turing’s Automatic Computing Engine (ACE) the concept of which dated from 1945: the Pilot ACE. In his spare time Strachey developed a program for the game of draughts, which he finished in February 1951. The game completely exhausted the Pilot ACE’s memory. The draughts program ran for the first time on 30 July 1951 at NPL. When Strachey heard about the Manchester Mark 1, which had a much bigger memory, he asked his former fellow-student Alan Turing for the manual and transcribed his program into the operation codes of that machine by around October 1951. The program could "play a complete game of draughts at a reasonable speed". He also wrote one of the first computer music programs, which played Baa Baa Black Sheep.[5]
Strachey worked for the National Research and Development Corporation (NRDC) from 1952 to 1959. While working on the St. Lawrence Seaway project, he was able to visit several computer centers in the United States and catalog their instruction sets. Later, he worked on programming both the Elliott 401 computer and the Ferranti Pegasus computer. He also worked on the analysis of vibration in aircraft, working briefly with Roger Penrose, and developed the concept of time-sharing.
In 1959, Strachey left NRDC to become a computer consultant working for NRDC, EMI, Ferranti and other organizations on a number of wide-ranging projects. This work included logical design for computers, providing autocode and later the design of high-level programming languages. For a contract to produce the autocode for the Ferranti Orion computer, Strachey hired Peter Landin who became his one assistant for the duration of Strachey's consulting period.
In 1962, while remaining a consultant, he accepted a position at Cambridge University.
In 1965, Strachey accepted a position at Oxford University as the first director of the Programming Research Group and later the University's first Professor of Computer Science and fellow of Wolfson College, Oxford. He collaborated with Dana Scott.
He developed the Combined Programming Language (CPL). His influential set of lecture notes Fundamental Concepts in Programming Languages formalized the distinction between L- and R- values (as seen in the C programming language). Strachey also coined the term currying, although he did not invent the underlying concept.
He was instrumental in the design of the Ferranti PEGASUS computer.
The macro language m4 derives much from Strachey's GPM (General Purpose Macrogenerator), one of the earliest macro expansion languages.[6]