Peter J. Landin
Encyclopedia
Peter John Landin was a British
computer scientist
. He was one of the first to realize that the lambda calculus
could be used to model a programming language, an insight that is essential to development of both functional programming
and denotational semantics
.
, where he attended King Edward VII School
; he graduated from Clare College
, Cambridge University. From 1960 to 1964, he was the assistant to Christopher Strachey
when the latter was an independent computer consultant in London
. Most of his work was published during this period and the brief time he worked for Univac
and at the Massachusetts Institute of Technology
in the United States
before taking a position at Queen Mary, University of London
. During the 1970s and 1980s, his efforts went into building the Computer Science department in Queen Mary College, developing courses and teaching students. On his retirement, he was appointed Emeritus Professor of Theoretical Computation at Queen Mary, University of London
.
At a workshop at the Science Museum
, London
, in 2001, on the history of programming semantics he spoke of how his scholarly career in computer science began in the late 1950s and of how he was much influenced by a study of McCarthy
's LISP
when the most commonly used language was Fortran
.
He was active in the definition of the ALGOL
programming language and cited by Tony Hoare as one of the people who taught him Algol 60 and hence facilitated his expression of powerful recursive algorithms:
Landin is responsible for inventing the SECD machine
, the first abstract process virtual machine
ever defined, and the ISWIM
programming language, defining the Landin off-side rule
and for coining the term syntactic sugar
. The off-side rule allows bounding scope declaration by use of white spaces as seen in languages such as Miranda, Haskell
, Python
and F# (Using the "light" syntax).
Another phrase originating with Landin is "The next 700 …" after his influential paper The next 700 programming languages. "700" was chosen because Landin had read in the Journal of the ACM
that there were already 700 programming languages in existence. The paper opens with the quotation "... today ... 1,700 special programming languages used to 'communicate' in over 700 application areas." It also includes the joke that
(GLF) during the early 1970s. He was once arrested as part of a GLF demonstration.
He was a dedicated cyclist and moved around London on his bike until it became physically impossible for him to do so.
, 11, 125–143 (1998).
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
computer scientist
Computer scientist
A computer scientist is a scientist who has acquired knowledge of computer science, the study of the theoretical foundations of information and computation and their application in computer systems....
. He was one of the first to realize that the lambda calculus
Lambda calculus
In mathematical logic and computer science, lambda calculus, also written as λ-calculus, is a formal system for function definition, function application and recursion. The portion of lambda calculus relevant to computation is now called the untyped lambda calculus...
could be used to model a programming language, an insight that is essential to development of both functional programming
Functional programming
In computer science, functional programming is a programming paradigm that treats computation as the evaluation of mathematical functions and avoids state and mutable data. It emphasizes the application of functions, in contrast to the imperative programming style, which emphasizes changes in state...
and denotational semantics
Denotational semantics
In computer science, denotational semantics is an approach to formalizing the meanings of programming languages by constructing mathematical objects which describe the meanings of expressions from the languages...
.
Academic
Landin was born in SheffieldSheffield
Sheffield is a city and metropolitan borough of South Yorkshire, England. Its name derives from the River Sheaf, which runs through the city. Historically a part of the West Riding of Yorkshire, and with some of its southern suburbs annexed from Derbyshire, the city has grown from its largely...
, where he attended King Edward VII School
King Edward VII School (Sheffield)
King Edward VII School is a secondary school and language college located in Sheffield, South Yorkshire, England. KES, named after the reigning monarch, was formed in 1905 when Wesley College was merged with Sheffield Royal Grammar School on the site of the former on Glossop Road...
; he graduated from Clare College
Clare College, Cambridge
Clare College is a constituent college of the University of Cambridge in Cambridge, England.The college was founded in 1326, making it the second-oldest surviving college of the University after Peterhouse. Clare is famous for its chapel choir and for its gardens on "the Backs"...
, Cambridge University. From 1960 to 1964, he was the assistant to Christopher Strachey
Christopher Strachey
Christopher Strachey was a British computer scientist. He was one of the founders of denotational semantics, and a pioneer in programming language design...
when the latter was an independent computer consultant in London
London
London is the capital city of :England and the :United Kingdom, the largest metropolitan area in the United Kingdom, and the largest urban zone in the European Union by most measures. Located on the River Thames, London has been a major settlement for two millennia, its history going back to its...
. Most of his work was published during this period and the brief time he worked for Univac
UNIVAC
UNIVAC is the name of a business unit and division of the Remington Rand company formed by the 1950 purchase of the Eckert-Mauchly Computer Corporation, founded four years earlier by ENIAC inventors J. Presper Eckert and John Mauchly, and the associated line of computers which continues to this day...
and at the Massachusetts Institute of Technology
Massachusetts Institute of Technology
The Massachusetts Institute of Technology is a private research university located in Cambridge, Massachusetts. MIT has five schools and one college, containing a total of 32 academic departments, with a strong emphasis on scientific and technological education and research.Founded in 1861 in...
in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
before taking a position at Queen Mary, University of London
Queen Mary, University of London
Queen Mary, University of London is a public research university located in London, United Kingdom and a constituent college of the federal University of London...
. During the 1970s and 1980s, his efforts went into building the Computer Science department in Queen Mary College, developing courses and teaching students. On his retirement, he was appointed Emeritus Professor of Theoretical Computation at Queen Mary, University of London
Queen Mary, University of London
Queen Mary, University of London is a public research university located in London, United Kingdom and a constituent college of the federal University of London...
.
At a workshop at the Science Museum
Science Museum (London)
The Science Museum is one of the three major museums on Exhibition Road, South Kensington, London in the Royal Borough of Kensington and Chelsea. It is part of the National Museum of Science and Industry. The museum is a major London tourist attraction....
, London
London
London is the capital city of :England and the :United Kingdom, the largest metropolitan area in the United Kingdom, and the largest urban zone in the European Union by most measures. Located on the River Thames, London has been a major settlement for two millennia, its history going back to its...
, in 2001, on the history of programming semantics he spoke of how his scholarly career in computer science began in the late 1950s and of how he was much influenced by a study of McCarthy
John McCarthy (computer scientist)
John McCarthy was an American computer scientist and cognitive scientist. He coined the term "artificial intelligence" , invented the Lisp programming language and was highly influential in the early development of AI.McCarthy also influenced other areas of computing such as time sharing systems...
's LISP
Lisp
A lisp is a speech impediment, historically also known as sigmatism. Stereotypically, people with a lisp are unable to pronounce sibilants , and replace them with interdentals , though there are actually several kinds of lisp...
when the most commonly used language was Fortran
Fortran
Fortran is a general-purpose, procedural, imperative programming language that is especially suited to numeric computation and scientific computing...
.
He was active in the definition of the ALGOL
ALGOL
ALGOL is a family of imperative computer programming languages originally developed in the mid 1950s which greatly influenced many other languages and became the de facto way algorithms were described in textbooks and academic works for almost the next 30 years...
programming language and cited by Tony Hoare as one of the people who taught him Algol 60 and hence facilitated his expression of powerful recursive algorithms:
"Around Easter 1961, a course on ALGOL 60ALGOL 60ALGOL 60 is a member of the ALGOL family of computer programming languages. It gave rise to many other programming languages, including BCPL, B, Pascal, Simula, C, and many others. ALGOL 58 introduced code blocks and the begin and end pairs for delimiting them...
was offered in BrightonBrightonBrighton is the major part of the city of Brighton and Hove in East Sussex, England on the south coast of Great Britain...
, EnglandEnglandEngland is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
, with Peter NaurPeter NaurPeter Naur is a Danish pioneer in computer science and Turing award winner. His last name is the N in the BNF notation , used in the description of the syntax for most programming languages...
, Edsger W. Dijkstra, and Peter Landin as tutors. … It was there that I first learned about recursive procedures and saw how to program the sorting method which I had earlier found such difficulty in explaining. It was there that I wrote the procedure, immodestly named QUICKSORT, on which my career as a computer scientist is founded. Due credit must be paid to the genius of the designers of ALGOL 60 who included recursion in their language and enabled me to describe my invention so elegantly to the world. I have regarded it as the highest goal of programming language design to enable good ideas to be elegantly expressed."
Landin is responsible for inventing the SECD machine
SECD machine
The SECD machine is a highly influential virtual machine and abstract machine intended as a target for functional programming language compilers. The letters stand for Stack, Environment, Code, Dump, the internal registers of the machine...
, the first abstract process virtual machine
Virtual machine
A virtual machine is a "completely isolated guest operating system installation within a normal host operating system". Modern virtual machines are implemented with either software emulation or hardware virtualization or both together.-VM Definitions:A virtual machine is a software...
ever defined, and the ISWIM
ISWIM
ISWIM is an abstract computer programming language devised by Peter J. Landin and first described in his article, The Next 700 Programming Languages, published in the Communications of the ACM in 1966...
programming language, defining the Landin off-side rule
Off-side rule
A computer programming language is said to adhere to the off-side rule if the scope of declarations in that language is expressed by their indentation. The term and the idea are attributed to Peter J. Landin, and the term can be seen as a pun on the offside law of football .- Definition :Peter J...
and for coining the term syntactic sugar
Syntactic sugar
Syntactic sugar is a computer science term that refers to syntax within a programming language that is designed to make things easier to read or to express....
. The off-side rule allows bounding scope declaration by use of white spaces as seen in languages such as Miranda, Haskell
Haskell (programming language)
Haskell is a standardized, general-purpose purely functional programming language, with non-strict semantics and strong static typing. It is named after logician Haskell Curry. In Haskell, "a function is a first-class citizen" of the programming language. As a functional programming language, the...
, Python
Python (programming language)
Python is a general-purpose, high-level programming language whose design philosophy emphasizes code readability. Python claims to "[combine] remarkable power with very clear syntax", and its standard library is large and comprehensive...
and F# (Using the "light" syntax).
Another phrase originating with Landin is "The next 700 …" after his influential paper The next 700 programming languages. "700" was chosen because Landin had read in the Journal of the ACM
Journal of the ACM
The Journal of the ACM is the flagship scientific journal of the Association for Computing Machinery . It is peer-reviewed and covers computer science in general, especially theoretical aspects. Its current editor-in-chief is Victor Vianu, from University of California, San Diego.The journal has...
that there were already 700 programming languages in existence. The paper opens with the quotation "... today ... 1,700 special programming languages used to 'communicate' in over 700 application areas." It also includes the joke that
"A possible first step in the research program is 1700 doctoral theses called "A Correspondence between x and Church'sa reference to his earlier paper. This dry sense of humour is expressed in many of his papers.Alonzo ChurchAlonzo Church was an American mathematician and logician who made major contributions to mathematical logic and the foundations of theoretical computer science. He is best known for the lambda calculus, Church–Turing thesis, Frege–Church ontology, and the Church–Rosser theorem.-Life:Alonzo Church...
λ-notationLambda calculusIn mathematical logic and computer science, lambda calculus, also written as λ-calculus, is a formal system for function definition, function application and recursion. The portion of lambda calculus relevant to computation is now called the untyped lambda calculus...
"
Political
Landin, who was bisexual, became involved with the Gay Liberation FrontGay Liberation Front
Gay Liberation Front was the name of a number of Gay Liberation groups, the first of which was formed in New York City in 1969, immediately after the Stonewall riots, in which police clashed with gay demonstrators.-The Gay Liberation Front:...
(GLF) during the early 1970s. He was once arrested as part of a GLF demonstration.
He was a dedicated cyclist and moved around London on his bike until it became physically impossible for him to do so.
Selected publications
Reprinted in Higher-Order and Symbolic ComputationHigher-Order and Symbolic Computation
Higher-Order and Symbol Computation is a computer science journal published by Springer Science+Business Media. It focusses on programming concepts and abstractions and programming language theory.- Editors :Former editors-in-chief of the journal have been:* Richard P...
, 11, 125–143 (1998).
External links
- Landin's website
- Program Verification and Semantics: The Early Work, BCS Computer Conservation SocietyComputer Conservation SocietyThe Computer Conservation Society is a British organization, founded in 1989. It is under the joint umbrella of the British Computer Society, the Science Museum in London, and the Museum of Science and Industry in Manchester. Many of the society's meetings are held at the Science Museum...
seminar, Science MuseumScience Museum (London)The Science Museum is one of the three major museums on Exhibition Road, South Kensington, London in the Royal Borough of Kensington and Chelsea. It is part of the National Museum of Science and Industry. The museum is a major London tourist attraction....
, London, UK, 5 June 2001 - Memorial talk on Landin's life by Olivier DanvyOlivier DanvyOlivier Danvy is a French computer scientist specializing in programming languages, partial evaluation, and continuations at the University of Aarhus in Denmark.He is notable for the number of scientific papers which acknowledge his help...
at ICFP 2009 - Peter Landin's talk at Program Verification and Semantics: The Early Work, 2001 (video)