The Discoveries of Continuations
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Kathleen Fisher Question: Interesting Answer in Algol
10/21/08 cs242! Lisp! Algol 60! Algol 68! Pascal! Kathleen Fisher! ML! Modula! Reading: “Concepts in Programming Languages” Chapter 5 except 5.4.5! Haskell! “Real World Haskell”, Chapter 0 and Chapter 1! (http://book.realworldhaskell.org/)! Many other languages:! Algol 58, Algol W, Euclid, EL1, Mesa (PARC), …! Thanks to John Mitchell and Simon Peyton Jones for some of these slides. ! Modula-2, Oberon, Modula-3 (DEC)! Basic Language of 1960! Simple imperative language + functions! Successful syntax, BNF -- used by many successors! real procedure average(A,n); statement oriented! real array A; integer n; No array bounds.! begin … end blocks (like C { … } )! begin if … then … else ! real sum; sum := 0; Recursive functions and stack storage allocation! for i = 1 step 1 until n Fewer ad hoc restrictions than Fortran! do General array references: A[ x + B[3] * y ] sum := sum + A[i]; Type discipline was improved by later languages! average := sum/n No “;” here.! Very influential but not widely used in US! end; Tony Hoare: “Here is a language so far ahead of its time that it was not only an improvement on its predecessors Set procedure return value by assignment.! but also on nearly all of its successors.”! Question:! Holes in type discipline! Is x := x equivalent to doing nothing?! Parameter types can be arrays, but! No array bounds! Interesting answer in Algol:! Parameter types can be procedures, but! No argument or return types for procedure parameters! integer procedure p; begin Problems with parameter passing mechanisms! -
A Universal Modular ACTOR Formalism for Artificial
Artificial Intelligence A Universal Modular ACTOR Formalism for Artificial Intelligence Carl Hewitt Peter Bishop Richard Steiger Abstract This paper proposes a modular ACTOR architecture and definitional method for artificial intelligence that is conceptually based on a single kind of object: actors [or, if you will, virtual processors, activation frames, or streams]. The formalism makes no presuppositions about the representation of primitive data structures and control structures. Such structures can be programmed, micro-coded, or hard wired 1n a uniform modular fashion. In fact it is impossible to determine whether a given object is "really" represented as a list, a vector, a hash table, a function, or a process. The architecture will efficiently run the coming generation of PLANNER-like artificial intelligence languages including those requiring a high degree of parallelism. The efficiency is gained without loss of programming generality because it only makes certain actors more efficient; it does not change their behavioral characteristics. The architecture is general with respect to control structure and does not have or need goto, interrupt, or semaphore primitives. The formalism achieves the goals that the disallowed constructs are intended to achieve by other more structured methods. PLANNER Progress "Programs should not only work, but they should appear to work as well." PDP-1X Dogma The PLANNER project is continuing research in natural and effective means for embedding knowledge in procedures. In the course of this work we have succeeded in unifying the formalism around one fundamental concept: the ACTOR. Intuitively, an ACTOR is an active agent which plays a role on cue according to a script" we" use the ACTOR metaphor to emphasize the inseparability of control and data flow in our model. -
Edsger Dijkstra: the Man Who Carried Computer Science on His Shoulders
INFERENCE / Vol. 5, No. 3 Edsger Dijkstra The Man Who Carried Computer Science on His Shoulders Krzysztof Apt s it turned out, the train I had taken from dsger dijkstra was born in Rotterdam in 1930. Nijmegen to Eindhoven arrived late. To make He described his father, at one time the president matters worse, I was then unable to find the right of the Dutch Chemical Society, as “an excellent Aoffice in the university building. When I eventually arrived Echemist,” and his mother as “a brilliant mathematician for my appointment, I was more than half an hour behind who had no job.”1 In 1948, Dijkstra achieved remarkable schedule. The professor completely ignored my profuse results when he completed secondary school at the famous apologies and proceeded to take a full hour for the meet- Erasmiaans Gymnasium in Rotterdam. His school diploma ing. It was the first time I met Edsger Wybe Dijkstra. shows that he earned the highest possible grade in no less At the time of our meeting in 1975, Dijkstra was 45 than six out of thirteen subjects. He then enrolled at the years old. The most prestigious award in computer sci- University of Leiden to study physics. ence, the ACM Turing Award, had been conferred on In September 1951, Dijkstra’s father suggested he attend him three years earlier. Almost twenty years his junior, I a three-week course on programming in Cambridge. It knew very little about the field—I had only learned what turned out to be an idea with far-reaching consequences. a flowchart was a couple of weeks earlier. -
Fiendish Designs
Fiendish Designs A Software Engineering Odyssey © Tim Denvir 2011 1 Preface These are notes, incomplete but extensive, for a book which I hope will give a personal view of the first forty years or so of Software Engineering. Whether the book will ever see the light of day, I am not sure. These notes have come, I realise, to be a memoir of my working life in SE. I want to capture not only the evolution of the technical discipline which is software engineering, but also the climate of social practice in the industry, which has changed hugely over time. To what extent, if at all, others will find this interesting, I have very little idea. I mention other, real people by name here and there. If anyone prefers me not to refer to them, or wishes to offer corrections on any item, they can email me (see Contact on Home Page). Introduction Everybody today encounters computers. There are computers inside petrol pumps, in cash tills, behind the dashboard instruments in modern cars, and in libraries, doctors’ surgeries and beside the dentist’s chair. A large proportion of people have personal computers in their homes and may use them at work, without having to be specialists in computing. Most people have at least some idea that computers contain software, lists of instructions which drive the computer and enable it to perform different tasks. The term “software engineering” wasn’t coined until 1968, at a NATO-funded conference, but the activity that it stands for had been carried out for at least ten years before that. -
Actor Model of Computation
Published in ArXiv http://arxiv.org/abs/1008.1459 Actor Model of Computation Carl Hewitt http://carlhewitt.info This paper is dedicated to Alonzo Church and Dana Scott. The Actor model is a mathematical theory that treats “Actors” as the universal primitives of concurrent digital computation. The model has been used both as a framework for a theoretical understanding of concurrency, and as the theoretical basis for several practical implementations of concurrent systems. Unlike previous models of computation, the Actor model was inspired by physical laws. It was also influenced by the programming languages Lisp, Simula 67 and Smalltalk-72, as well as ideas for Petri Nets, capability-based systems and packet switching. The advent of massive concurrency through client- cloud computing and many-core computer architectures has galvanized interest in the Actor model. An Actor is a computational entity that, in response to a message it receives, can concurrently: send a finite number of messages to other Actors; create a finite number of new Actors; designate the behavior to be used for the next message it receives. There is no assumed order to the above actions and they could be carried out concurrently. In addition two messages sent concurrently can arrive in either order. Decoupling the sender from communications sent was a fundamental advance of the Actor model enabling asynchronous communication and control structures as patterns of passing messages. November 7, 2010 Page 1 of 25 Contents Introduction ............................................................ 3 Fundamental concepts ............................................ 3 Illustrations ............................................................ 3 Modularity thru Direct communication and asynchrony ............................................................. 3 Indeterminacy and Quasi-commutativity ............... 4 Locality and Security ............................................ -
The Discoveries of Continuations
LISP AND SYMBOLIC COMPUTATION: An InternationM JournM, 6, 233-248, 1993 @ 1993 Kluwer Academic Publishers - Manufactured in The Nett~eriands The Discoveries of Continuations JOHN C. REYNOLDS ( [email protected] ) School of Computer Science Carnegie Mellon University Pittsburgh, PA 15213-3890 Keywords: Semantics, Continuation, Continuation-Passing Style Abstract. We give a brief account of the discoveries of continuations and related con- cepts by A. van Vv'ijngaarden, A. W. Mazurkiewicz, F. L. Morris, C. P. Wadsworth. J. H. Morris, M. J. Fischer, and S. K. Abdali. In the early history of continuations, basic concepts were independently discovered an extraordinary number of times. This was due less to poor communication among computer scientists than to the rich variety of set- tings in which continuations were found useful: They underlie a method of program transformation (into continuation-passing style), a style of def- initionM interpreter (defining one language by an interpreter written in another language), and a style of denotational semantics (in the sense of Scott and Strachey). In each of these settings, by representing "the mean- ing of the rest of the program" as a function or procedure, continnations provide an elegant description of a variety of language constructs, including call by value and goto statements. 1. The Background In the early 1960%, the appearance of Algol 60 [32, 33] inspired a fi~rment of research on the implementation and formal definition of programming languages. Several aspects of this research were critical precursors of the discovery of continuations. The ability in Algol 60 to jump out of blocks, or even procedure bod- ies, forced implementors to realize that the representation of a label must include a reference to an environment. -
PRME Conference Programme V1.Indd 1 21/06/2018 23:49 Contents
The School of Business and Management, Queen Mary University of London is delighted to be hosting the 5th UN PRME UK and Ireland Conference 5th UK and Ireland PRME Conference Inclusive Responsible Management Education in an Era of Precarity 25-27 June 2018 PRME is working to help achieve UN sustainable development goals QM18-0002 - UN PRME Conference Programme v1.indd 1 21/06/2018 23:49 Contents Welcome to Queen Mary, University of London ...........................3 Conference Information .....................................................................4 Conference Dinners ...........................................................................4 Conference Theme .............................................................................6 Conference Schedule ........................................................................7 Speaker Biographies ....................................................................... 12 Paper Abstracts................................................................................ 16 2 www.busman.qmul.ac.uk QM18-0002 - UN PRME Conference Programme v1.indd 2 21/06/2018 23:49 Welcome to Queen Mary, University of London! Welcome to 5th UN PRME UK and Ireland Conference. Our Theme this year ‘Leaving no one behind’ - Inclusive Responsible Management Education in an Era of Precarity’ is resonant with the ethos and spirit of the School of Business and Management at Queen Mary. We are indeed honoured to be playing host to this prestigious event as the conference highlights our intrinsic commitment -
A Rational Deconstruction of Landin's J Operator
BRICS RS-06-4 Danvy & Millikin: A Rational Deconstruction of Landin’s J Operator BRICS Basic Research in Computer Science A Rational Deconstruction of Landin’s J Operator Olivier Danvy Kevin Millikin BRICS Report Series RS-06-4 ISSN 0909-0878 February 2006 Copyright c 2006, Olivier Danvy & Kevin Millikin. BRICS, Department of Computer Science University of Aarhus. All rights reserved. Reproduction of all or part of this work is permitted for educational or research use on condition that this copyright notice is included in any copy. See back inner page for a list of recent BRICS Report Series publications. Copies may be obtained by contacting: BRICS Department of Computer Science University of Aarhus IT-parken, Aabogade 34 DK–8200 Aarhus N Denmark Telephone: +45 8942 9300 Telefax: +45 8942 5601 Internet: [email protected] BRICS publications are in general accessible through the World Wide Web and anonymous FTP through these URLs: http://www.brics.dk ftp://ftp.brics.dk This document in subdirectory RS/06/4/ A Rational Deconstruction of Landin’s J Operator∗ Olivier Danvy and Kevin Millikin BRICS† Department of Computer Science University of Aarhus‡ February 28, 2006 Abstract Landin’s J operator was the first control operator for functional languages, and was specified with an extension of the SECD machine. Through a se- ries of meaning-preserving transformations (transformation into continu- ation-passing style (CPS) and defunctionalization) and their left inverses (transformation into direct style and refunctionalization), we present a compositional evaluation function corresponding to this extension of the SECD machine. We then characterize the J operator in terms of CPS and in terms of delimited-control operators in the CPS hierarchy. -
Publiek Domein Laat Bedrijven Te Veel Invullen
Steven Pemberton, software-uitvinder en bouwer aan het World wide web Publiek domein laat bedrijven te veel invullen De Brit Steven Pemberton is al sinds 1982 verbonden aan het Centrum voor Wiskunde Informatica (CWI) in Amsterdam. Ook hij is een aartsvader van het internet. Specifiek van het World wide web, waarvan hij destijds dicht bij de uitvinding zat. Steven blijft naar de toekomst kijken, nog met dezelfde fraaie idealen. C.V. 19 februari 1953 geboren te Ash, Surrey, Engeland 1972-1975 Programmeur Research Support Unit Sussex University 1975-1977 Research Programmer Manchester University 1977-1982 Docent Computerwetenschap Brighton University 1982-heden Onderzoeker aan het Centrum voor Wiskunde & Informatica (CWI) Verder: 1993–1999 Hoofdredacteur SIGCHI Bulletin en ACM Interactions 1999–2009 Voorzitter HTML en XHTML2 werkgroepen van W3C 2008-heden Voorzitter XForms werkgroep W3C The Internet Guide to Amsterdam Homepage bij het CWI Op Wikipedia 1 Foto’s: Frank Groeliken Tekst: Peter Olsthoorn Steven Pemberton laat zich thuis interviewen, op een typisch Amsterdamse plek aan de Bloemgracht, op de 6e etage van een pakhuis uit 1625 met uitzicht op de Westertoren. Hij schrijft aan een boek, een voortzetting van zijn jaarlijkse lezing in Pakhuis de Zwijger, met in 2011 The Computer as Extended Phenotype (Computers, Genes and You) als titel. Wat is je thema? “De invloed van hard- en software op de maatschappij, vanuit de nieuwe technologie bezien. ‘Fenotype’ gaat over computers als product van onze genen, als een onderdeel van de evolutie. Je kunt de aanwas van succesvolle genen zien als een vorm van leren, of een vorm van geheugen. -
An Interview with Tony Hoare ACM 1980 A.M. Turing Award Recipient
1 An Interview with 2 Tony Hoare 3 ACM 1980 A.M. Turing Award Recipient 4 (Interviewer: Cliff Jones, Newcastle University) 5 At Tony’s home in Cambridge 6 November 24, 2015 7 8 9 10 CJ = Cliff Jones (Interviewer) 11 12 TH = Tony Hoare, 1980 A.M. Turing Award Recipient 13 14 CJ: This is a video interview of Tony Hoare for the ACM Turing Award Winners project. 15 Tony received the award in 1980. My name is Cliff Jones and my aim is to suggest 16 an order that might help the audience understand Tony’s long, varied, and influential 17 career. The date today is November 24th, 2015, and we’re sitting in Tony and Jill’s 18 house in Cambridge, UK. 19 20 Tony, I wonder if we could just start by clarifying your name. Initials ‘C. A. R.’, but 21 always ‘Tony’. 22 23 TH: My original name with which I was baptised was Charles Antony Richard Hoare. 24 And originally my parents called me ‘Charles Antony’, but they abbreviated that 25 quite quickly to ‘Antony’. My family always called me ‘Antony’, but when I went to 26 school, I think I moved informally to ‘Tony’. And I didn’t move officially to ‘Tony’ 27 until I retired and I thought ‘Sir Tony’ would sound better than ‘Sir Antony’. 28 29 CJ: Right. If you agree, I’d like to structure the discussion around the year 1980 when 30 you got the Turing Award. I think it would be useful for the audience to understand 31 just how much you’ve done since that award. -
Literaturverzeichnis
Literaturverzeichnis ABD+99. Dirk Ansorge, Klaus Bergner, Bernhard Deifel, Nicholas Hawlitzky, Christoph Maier, Barbara Paech, Andreas Rausch, Marc Sihling, Veronika Thurner, and Sascha Vogel: Managing componentware development – software reuse and the V-Modell process. In M. Jarke and A. Oberweis (editors): Advanced Information Systems Engineering, 11th International Conference CAiSE’99, Heidelberg, volume 1626 of Lecture Notes in Computer Science, pages 134–148. Springer, 1999, ISBN 3-540-66157-3. Abr05. Jean-Raymond Abrial: The B-Book. Cambridge University Press, 2005. AJ94. Samson Abramsky and Achim Jung: Domain theory. In Samson Abramsky, Dov M. Gabbay, and Thomas Stephen Edward Maibaum (editors): Handbook of Logic in Computer Science, volume 3, pages 1–168. Clarendon Press, 1994. And02. Peter Bruce Andrews: An introduction to mathematical logic and type theory: To Truth Through Proof, volume 27 of Applied Logic Series. Springer, 2nd edition, July 2002, ISBN 978-94-015-9934-4. AVWW95. Joe Armstrong, Robert Virding, Claes Wikström, and Mike Williams: Concurrent programming in Erlang. Prentice Hall, 2nd edition, 1995. Bac78. Ralph-Johan Back: On the correctness of refinement steps in program develop- ment. PhD thesis, Åbo Akademi, Department of Computer Science, Helsinki, Finland, 1978. Report A–1978–4. Bas83. Günter Baszenski: Algol 68 Preludes for Arithmetic in Z and Q. Bochum, 2nd edition, September 1983. Bau75. Friedrich Ludwig Bauer: Software engineering. In Friedrich Ludwig Bauer (editor): Advanced Course: Software Engineering, Reprint of the First Edition (February 21 – March 3, 1972), volume 30 of Lecture Notes in Computer Science, pages 522–545. Springer, 1975. Bau82. Rüdeger Baumann: Programmieren mit PASCAL. Chip-Wissen. Vogel-Verlag, Würzburg, 1982. -
Final Version
Centrum Wiskunde & Informatica Software Engineering Software ENgineering A comparison between the ALGOL 60 implementations on the Electrologica X1 and the Electrologica X8 F.E.J. Kruseman Aretz REPORT SEN-E0801 SEPTEMBER 2008 Centrum Wiskunde & Informatica (CWI) is the national research institute for Mathematics and Computer Science. It is sponsored by the Netherlands Organisation for Scientific Research (NWO). CWI is a founding member of ERCIM, the European Research Consortium for Informatics and Mathematics. CWI's research has a theme-oriented structure and is grouped into four clusters. Listed below are the names of the clusters and in parentheses their acronyms. Probability, Networks and Algorithms (PNA) Software Engineering (SEN) Modelling, Analysis and Simulation (MAS) Information Systems (INS) Copyright © 2008, Centrum Wiskunde & Informatica P.O. Box 94079, 1090 GB Amsterdam (NL) Kruislaan 413, 1098 SJ Amsterdam (NL) Telephone +31 20 592 9333 Telefax +31 20 592 4199 ISSN 1386-369X A comparison between the ALGOL 60 implementations on the Electrologica X1 and the Electrologica X8 ABSTRACT We compare two ALGOL 60 implementations, both developed at the Mathematical Centre in Amsterdam, forerunner of the CWI. They were designed for Electrologica hardware, the EL X1 from 1958 and the EL X8 from 1965. The X1 did not support ALGOL 60 implementation at all. Its ALGOl 60 system was designed by Dijkstra and Zonneveld and completed in 1960. Although developed as an academic exercise it soon was heavily used and appreciated. The X8, successor of the X1 and (almost) upwards compatible to it, had a number of extensions chosen specifically to support ALGOL 60 implementation. The ALGOL 60 system, developed by Nederkoorn and Kruseman Aretz, was completed even before the first delivery of an X8.