ALGOL 60(short forAlgorithmic Language 1960) is a member of theALGOLfamily of computerprogramming languages.It followed on fromALGOL 58which had introducedcode blocksand thebeginandendpairs for delimiting them, representing a key advance in the rise ofstructured programming.ALGOL 60 was one of the first languages implementing function definitions (that could be invoked recursively). ALGOL 60 function definitions could benestedwithin one another (which was first introduced by any programming language), withlexical scope.It gave rise to many other languages, includingCPL,PL/I,Simula,BCPL,B,Pascal,andC.Practically every computer of the era had asystems programming languagebased on ALGOL 60 concepts.
| Paradigms | procedural,imperative,structured |
|---|---|
| Family | ALGOL |
| Designed by | Backus,Bauer,Green,Katz,McCarthy,Naur,Perlis,Rutishauser,Samelson,van Wijngaarden,Vauquois,Wegstein,Woodger |
| First appeared | 1960 |
| Typing discipline | Static,strong |
| Scope | Lexical |
| Influenced by | |
| ALGOL 58 | |
| Influenced | |
| Most subsequent imperative languages (so-calledALGOL-likelanguages), e.g.,PL/I,Simula,CPL,Pascal,Ada,C | |
Niklaus Wirthbased his ownALGOL Won ALGOL 60 before moving to developPascal.Algol-W was intended to be the next generation ALGOL but theALGOL 68committee decided on a design that was more complex and advanced rather than a cleaned simplified ALGOL 60. The official ALGOL versions are named after the year they were first published. ALGOL 68 is substantially different from ALGOL 60 and was criticised partially for being so, so that in general "ALGOL" refers to dialects of ALGOL 60.
Standardization
editALGOL 60 – withCOBOL– were the first languages to seek standardization.
- ISO 1538:1984Programming languages – ALGOL 60 (stabilized)
- ISO/TR 1672:1977Hardware representation of ALGOL basic symbols... (now withdrawn)
History
editALGOL 60 was used mostly by research computer scientists in the United States and in Europe. Its use in commercial applications was hindered by the absence of standardinput/outputfacilities in its description and the lack of interest in the language by large computer vendors. ALGOL 60 did however become the standard for the publication of algorithms and had a profound effect on future language development.
John Backusdeveloped theBackus normal formmethod of describing programming languages specifically for ALGOL 58. It was revised and expanded byPeter Naurfor ALGOL 60, and atDonald Knuth's suggestion renamedBackus–Naur form.[1]
Peter Naur: "As editor of the ALGOL Bulletin I was drawn into the international discussions of the language and was selected to be member of the European language design group in November 1959. In this capacity I was the editor of the ALGOL 60 report, produced as the result of the ALGOL 60 meeting in Paris in January 1960."[2]
The following people attended the meeting in Paris (from January 11 to 16):
- Friedrich Ludwig Bauer,Peter Naur,Heinz Rutishauser,Klaus Samelson,Bernard Vauquois,Adriaan van Wijngaarden,andMichael Woodger(from Europe)
- John Warner Backus,Julien Green,Charles Katz,John McCarthy,Alan Jay Perlis,andJoseph Henry Wegstein(from the USA).
Alan Perlis gave a vivid description of the meeting: "The meetings were exhausting, interminable, and exhilarating. One became aggravated when one's good ideas were discarded along with the bad ones of others. Nevertheless, diligence persisted during the entire period. The chemistry of the 13 was excellent."
The language originally did not includerecursion.It was inserted into the specification at the last minute, against the wishes of some of the committee.[3]
ALGOL 60 inspired many languages that followed it.Tony Hoareremarked: "Here is a language so far ahead of its time that it was not only an improvement on its predecessors but also on nearly all its successors."[4][5]
ALGOL 60 implementations timeline
editTo date there have been at least 70 augmentations, extensions, derivations and sublanguages of ALGOL 60.[6]
| Name | Year | Author | State | Description | Target CPU |
|---|---|---|---|---|---|
| X1 ALGOL 60 | August 1960[7] | Edsger W. DijkstraandJaap A. Zonneveld |  Netherlands |
First implementation of ALGOL 60[8] | Electrologica X1 |
| Algol | 1960[9] | Edgar T. Irons |  USA |
ALGOL 60 | CDC 1604 |
| Burroughs Algol (Several variants) |
1961 | Burroughs Corporation(with participation byHoare,Dijkstra,and others) | USA |
Basis of theBurroughs(and nowUnisysMCPbased) computers | Burroughs Large Systems and midrange systems |
| Case ALGOL | 1961 | USA |
Simulawas originally contracted as a simulation extension of the Case ALGOL | UNIVAC 1107 | |
| GOGOL | 1961 | William M. McKeeman | USA |
For ODIN time-sharing system | PDP-1 |
| DASK ALGOL | 1961 | Peter Naur,Jørn Jensen |  Denmark |
ALGOL 60 | DASK at Regnecentralen |
| SMIL ALGOL | 1962 | Torgil Ekman,Carl-Erik Fröberg |  Sweden |
ALGOL 60 | SMILatLund University |
| GIER ALGOL | 1962 | Peter Naur,Jørn Jensen | Denmark |
ALGOL 60 | GIER at Regnecentralen |
| Dartmouth ALGOL 30[10] | 1962 | Thomas Eugene Kurtz,Stephen J. Garland,Robert F. Hargraves,Anthony W. Knapp,Jorge LLacer | USA |
ALGOL 60 | LGP-30 |
| Alcor Mainz 2002 | 1962 | Ursula Hill-Samelson, Hans Langmaack |  Germany |
Siemens 2002 | |
| ALCOR-Illinois 7090 | 1962 [11][12] |
Manfred Paul,Hans Rüdiger Wiehle,David Gries,andRudolf Bayer | USA,West Germany
|
ALGOL 60 Implemented atIllinoisand theTH München,1962-1964 |
IBM 7090 |
| USS 90 Algol | 1962 | L. Petrone |  Italy |
||
| Elliott ALGOL | 1962 | C. A. R. Hoare |  UK |
Discussed in his 1980Turing Awardlecture | Elliott 803& the Elliott 503 |
| ALGOL 60 | 1962 | Roland Strobel[13] |  East Germany |
Implemented by the Institute for Applied Mathematics,German Academy of Sciences at Berlin | Zeiss-Rechenautomat ZRA 1 |
| ALGOL 60 | 1962 | Bernard Vauquois,Louis Bolliet[14] |  France
|
Institut d'Informatique et Mathématiques Appliquées de Grenoble (IMAG) and Compagnie des Machines Bull | Bull Gamma 60 |
| Algol Translator | 1962 | G. van der Mey andW.L. van der Poel | Netherlands |
Staatsbedrijf der Posterijen, Telegrafie en Telefonie | ZEBRA |
| Kidsgrove Algol | 1963 | F. G. Duncan | UK |
English Electric CompanyKDF9 | |
| SCALP[15] | 1963 | Stephen J. Garland,Anthony W. Knapp,Thomas Eugene Kurtz | USA |
Self-Contained ALgol Processorfor a subset of ALGOL 60 | LGP-30 |
| VALGOL | 1963 | Val Schorre | USA |
A test of theMETA IIcompiler compiler | |
| FP6000 Algol | 1963 | Roger Moore |  Canada |
written forSaskatchewan Power Corp | FP6000 |
| Whetstone | 1964 | Brian Randelland Lawford John Russell | UK |
Atomic Power Division of English Electric Company. Precursor toFerranti Pegasus,National Physical LaboratoriesACEandEnglish Electric DEUCEimplementations | English Electric CompanyKDF9 |
| ALGOL 60 | 1964 | Jean-Claude Boussard[16] | France |
Institut d'informatique et mathématiques appliquées de Grenoble | IBM 7090 |
| ALGOL-GENIUS | 1964 | Börje Langefors | Sweden |
AddedCOBOL-inspired data records and I/O | DatasaabD-21 |
| ALGOL 60 | 1965 | Claude Pair[17] | France |
Centre de calcul de la Faculté des Sciences de Nancy | IBM 1620 |
| Dartmouth ALGOL | 1965 | Stephen J. Garland,Sarr Blumson, Ron Martin | USA |
ALGOL 60 | Dartmouth Time-Sharing Systemfor theGE 235 |
| NU ALGOL | 1965 |  Norway |
UNIVAC | ||
| ALGOL 60 | 1965[18] | F.E.J. Kruseman Aretz | Netherlands |
MC compiler for the EL-X8 | Electrologica X8 |
| ALGEK | 1965 |  Soviet Union |
Minsk-22 | АЛГЭК, based on ALGOL 60 andCOBOLsupport, for economical tasks | |
| MALGOL | 1966 | publ. A. Viil, M Kotli & M. Rakhendi, |  Estonian SSR |
Minsk-22 | |
| ALGAMS | 1967 | GAMS group (ГАМС, группа автоматизации программирования для машин среднего класса), cooperation of Comecon Academies of Science | Comecon | Minsk-22,laterES EVM,BESM | |
| ALGOL/ZAM | 1967 |  Poland |
PolishZAMcomputer | ||
| Chinese Algol | 1972 |  China |
Chinese characters, expressed via the Symbol system | ||
| DG/L | 1972 | USA |
DGEclipsefamily of Computers | ||
| NASE | 1990 | Erik Schoenfelder | Germany |
Interpreter | Linux and MS Windows |
| MARST | 2000 | Andrew Makhorin |  Russia |
ALGOL 60 to C translator | All CPUs supported by the GNU Compiler Collection; MARST is part of the GNU project |
The Burroughs dialects included special system programming dialects such asESPOLandNEWP.
Properties
editALGOL 60 as officially defined had no I/O facilities; implementations defined their own in ways that were rarely compatible with each other. In contrast, ALGOL 68 offered an extensive library oftransput(ALGOL 68 parlance for input/output) facilities.
ALGOL 60 provided twoevaluation strategiesforparameterpassing: the commoncall-by-value,andcall-by-name.The procedure declaration specified, for each formal parameter, which was to be used:valuespecified for call-by-value, and omitted for call-by-name. Call-by-name has certain effects in contrast tocall-by-reference.For example, without specifying the parameters asvalueorreference,it is impossible to develop a procedure that will swap the values of two parameters if the actual parameters that are passed in are an integer variable and an array that is indexed by that same integer variable.[19]Think of passing a pointer to swap(i, A[i]) in to a function. Now that every time swap is referenced, it's reevaluated. Say i:= 1 and A[i]:= 2, so every time swap is referenced it'll return the other combination of the values ([1,2], [2,1], [1,2] and so on). A similar situation occurs with a random function passed as actual argument.
Call-by-name is known by many compiler designers for the interesting "thunks"that are used to implement it.Donald Knuthdevised the "man or boy test"to separate compilers that correctly implemented"recursionand non-local references. "This test contains an example of call-by-name.
ALGOL 60 Reserved words and restricted identifiers
editThere are 35 such reserved words in the standardBurroughs Large Systemssub-language:
ALPHAARRAYBEGINBOOLEANCOMMENTCONTINUEDIRECTDODOUBLEELSEENDEVENTFALSEFILEFORFORMATGOIFINTEGERLABELLISTLONGOWNPOINTERPROCEDUREREALSTEPSWITCHTASKTHENTRUEUNTILVALUEWHILEZIP
There are 71 such restricted identifiers in the standard Burroughs Large Systems sub-language:
ACCEPTANDATTACHBYCALLCASECAUSECLOSEDEALLOCATEDEFINEDETACHDISABLEDISPLAYDIVDUMPENABLEEQLEQVEXCHANGEEXTERNALFILLFORWARDGEQGTRIMPININTERRUPTISLBLEQLIBERATELINELOCKLSSMERGEMODMONITORMUXNEQNONOTONOPENOROUTPICTUREPROCESSPROCUREPROGRAMDUMPRBREADRELEASEREPLACERESETRESIZEREWINDRUNSCANSEEKSETSKIPSORTSPACESWAPTHRUTIMESTOWAITWHENWITHWRITE
and also the names of all the intrinsic functions.
Standard operators
edit| Priority | Operator | |
|---|---|---|
| first arithmetic | first | ↑ (power) |
| second | ×, / (real), ÷ (integer) | |
| third | +, - | |
| second | <, ≤, =, ≥, >, ≠ | |
| third | ¬ (not) | |
| fourth | ∧ (and) | |
| fifth | ∨ (or) | |
| sixth | ⊃ (implication) | |
| seventh | ≡ (equivalence) | |
Examples and portability issues
editCode sample comparisons
editALGOL 60
editprocedureAbsmax(a) Size:(n, m) Result:(y) Subscripts:(i, k); valuen, m;arraya;integern, m, i, k;realy; commentThe absolute greatest element of the matrix a, of size n by m, is copied to y, and the subscripts of this element to i and k; begin integerp, q; y:= 0; i:= k:= 1; forp:= 1step1untilndo forq:= 1step1untilmdo ifabs(a[p, q]) > ythen beginy:= abs(a[p, q]); i:= p; k:= q end endAbsmax
Implementations differ in how the text in bold must be written. The word 'INTEGER', including the quotation marks, must be used in some implementations in place ofinteger,above, therebydesignatingit as a special keyword.
Following is an example of how to produce a table usingElliott 803ALGOL:[20]
FLOATING POINT ALGOL TEST' BEGIN REAL A,B,C,D' READ D' FOR A:= 0.0 STEP D UNTIL 6.3 DO BEGIN PRINTPUNCH(3),££L??' B:= SIN(A)' C:= COS(A)' PRINTPUNCH(3),SAMELINE,ALIGNED(1,6),A,B,C' END' END'
ALGOL 60 family
editSince ALGOL 60 had no I/O facilities, there is no portablehello world programin ALGOL. The following program could (and still will) compile and run on an ALGOL implementation for a Unisys A-Series mainframe, and is a straightforward simplification of code taken from The Language Guide[21]at theUniversity of Michigan-Dearborn Computer and Information Science Department Hello world! ALGOL Example Program page.[22]
BEGIN FILE F(KIND=REMOTE); EBCDICARRAY E[0:11]; REPLACE E BY "HELLO WORLD!"; WRITE(F, *, E); END.
Where * etc. represented a format specification as used in FORTRAN, e.g.[23]
A simpler program using an inline format:
BEGIN
FILEF(KIND=REMOTE);
WRITE(F,<"HELLO WORLD!">);
END.
An even simpler program using the Display statement:
BEGINDISPLAY("HELLO WORLD!")END.
An alternative example, using Elliott Algol I/O is as follows. Elliott Algol used different characters for "open-string-quote" and "close-string-quote", represented here by‘and’.
programHiFolks;
begin
print‘Helloworld’
end;
Here's a version for the Elliott 803 Algol (A104) The standard Elliott 803 used 5-hole paper tape and thus only had upper case. The code lacked any quote characters so£(pound sign) was used for open quote and?(question mark) for close quote. Special sequences were placed in double quotes (e.g., £L?? produced a new line on the teleprinter).
HIFOLKS' BEGIN PRINT £HELLO WORLD£L??' END'
TheICT 1900 seriesAlgol I/O version allowed input from paper tape or punched card. Paper tape 'full' mode allowed lower case. Output was to a line printer. Note use of '(', ')', and %.[24]
'PROGRAM' (HELLO)
'BEGIN'
'COMMENT' OPEN QUOTE IS '(', CLOSE IS ')', PRINTABLE SPACE HAS TO
BE WRITTEN AS % BECAUSE SPACES ARE IGNORED;
WRITE TEXT('('HELLO%WORLD')');
'END'
'FINISH'
LEAP
editLEAP is an extension to the ALGOL 60 programming language which provides an associative memory of triples. The three items in a triple denote the association that an Attribute of an Object has a specific Value. LEAP was created by Jerome Feldman (University of California Berkeley) and Paul Rovner (MIT Lincoln Lab) in 1967. LEAP was also implemented in SAIL.
See also
editReferences
edit- ^Knuth, Donald E.(December 1964)."Backus normal Form vs Backus Naur Form".Communications of the ACM.7(12): 735–6.doi:10.1145/355588.365140.S2CID47537431.
- ^ACM Award Citation / Peter Naur,2005
- ^van Emden, Maarten (2014)."How recursion got into programming: a tale of intrigue, betrayal, and advanced programming-language semantics".A Programmer's Place.
- ^Hoare, C.A.R.(December 1973)."Hints on Programming Language Design"(PDF).p. 27.(This statement is sometimes erroneously attributed toEdsger W. Dijkstra,also involved in implementing the first ALGOL 60compiler.)
- ^Abelson, Hal;Dybvig, R. K.;et al. Rees, Jonathan; Clinger, William (eds.)."Revised(3) Report on the Algorithmic Language Scheme (Dedicated to the Memory of ALGOL 60)".Retrieved2009-10-20.
- ^The Encyclopedia of Computer LanguagesArchivedSeptember 27, 2011, at theWayback Machine
- ^Daylight, E. G. (2011)."Dijkstra's Rallying Cry for Generalization: the Advent of the Recursive Procedure, late 1950s – early 1960s".The Computer Journal.54(11): 1756–1772.doi:10.1093/comjnl/bxr002.
- ^Kruseman Aretz, F.E.J. (30 June 2003)."The Dijkstra-Zonneveld ALGOL 60 compiler for the Electrologica X1"(PDF).Software Engineering.History of Computer Science. Amsterdam: Centrum Wiskunde & Informatica.ISSN1386-3711.Archived fromthe original(PDF)on 2004-01-17.
- ^Irons, Edgar T.,A syntax directed compiler for ALGOL 60, Communications of the ACM, Vol. 4, p. 51. (Jan. 1961)
- ^Kurtz, Thomas E. (1978). "BASIC".History of programming languages.pp. 515–537.doi:10.1145/800025.1198404.ISBN0127450408.
- ^Gries, D.; Paul, M.; Wiehle, H. R (1965)."Some techniques used in the ALCOR Illinois 7090".Communications of the ACM.8(8): 496–500.doi:10.1145/365474.365511.S2CID18365024.
- ^Bayer, R.; Gries, D.; Paul, M.; Wiehle, H. R. (1967)."The ALCOR Illinois 7090/7094 post mortem dump".Communications of the ACM.10(12): 804–808.doi:10.1145/363848.363866.S2CID3783605.
- ^Rechenautomaten mit Trommelspeicher,Förderverein der Technischen Sammlung Dresden
- ^Mounier-Kuhn, Pierre (2014)."Algol in France: From Universal Project to Embedded Culture".IEEE Annals of the History of Computing.36(4): 6.ISSN1058-6180.
- ^Kurtz,op. cit.,page 517.
- ^Boussard, Jean-Claude (June 1964).Etude et réalisation d'un compilateur Algol60 sur calculateur éléctronique du type IBM 7090/94 et 7040/44[Design and implementation of a compiler Algol60 on electronic calculator IBM 7090/94 and 7040/44] (PhD) (in French). Université Joseph-Fourier - Grenoble I.
- ^Claude Pair (27 April 1965).Description d'un compilateur ALGOL.European Région 1620 Users Group.IBM.
- ^Kruseman Aretz, F.E.J. (1973).An Algol 60 compiler in Algol 60.Mathematical Centre Tracts. Amsterdam: Mathematisch Centrum.
- ^Aho, Alfred V.;Sethi, Ravi;Ullman, Jeffrey D.(1986).Compilers: Principles, Techniques, and Tools(1st ed.). Addison-Wesley.ISBN978-0-201-10194-2.,Section 7.5, and references therein
- ^"803 ALGOL",the manual forElliott 803ALGOL
- ^"The ALGOL Programming Language".www.engin.umd.umich.edu.Archived fromthe originalon 10 February 2010.Retrieved11 January2022.
- ^"Hello world! Example Program".www.engin.umd.umich.edu.Archived fromthe originalon 4 February 2010.Retrieved11 January2022.
- ^Fortran# "Hello, World!" example
- ^"ICL 1900 series: Algol Language".ICL Technical Publication 3340. 1965.
Further reading
edit- Dijkstra, Edsger W.(1961)."ALGOL 60 Translation: An ALGOL 60 Translator for the X1 and Making a Translator for ALGOL 60(PDF)(Technical report). Amsterdam: Mathematisch Centrum. 35.
- Randell, Brian;Russell, Lawford John (1964).ALGOL 60 Implementation: The Translation and Use of ALGOL 60 Programs on a Computer.Academic Press.OCLC526731.The design of theWhetstone Compiler.One of the early published descriptions of implementing a compiler. See the related papers:Whetstone Algol Revisited,andThe Whetstone KDF9 ALGOL TranslatorbyBrian Randell
- Goos, Gerhard[in German](2017-08-07).Geschichte der deutschsprachigen Informatik - Programmiersprachen und Übersetzerbau[History of informatics in German-speaking countries - Programming languages and compiler design](PDF)(in German). Karlsruhe, Germany: Fakultät für Informatik,Karlsruhe Institute of Technology(KIT).Archived(PDF)from the original on 2022-05-19.Retrieved2022-11-14.(11 pages)
External links
edit- Revised Report on the Algorithmic Language ALGOL 60by Peter Naur, et al. ALGOL definition
- A BNFsyntax summaryof ALGOL 60
- "The Emperor's Old Clothes"– Hoare's 1980 ACM Turing Award speech, which discusses ALGOL history and his involvement
- MARST,a free ALGOL-to-C translator
- An Implementation of ALGOL 60 for the FP6000Archived2020-07-25 at theWayback MachineDiscussion of some implementation issues.
- Naur, Peter(August 1978)."The European Side of the Last Phase of the Development of ALGOL 60".ACM SIGPLAN Notices.13(8): 15–44.doi:10.1145/960118.808370.S2CID15552479.
- Edinburgh University wrote compilers for Algol60 (later updated for Algol60M) based on their Atlas Autocode compilers initially bootstrapped from the Atlas to the KDF-9. The Edinburgh compilers generated code for the ICL1900, the ICL4/75 (an IBM360 clone), and the ICL2900. Here is theBNF for Algol60Archived2020-05-15 at theWayback Machineand theICL2900 compiler sourceArchived2020-05-15 at theWayback Machine,library documentationArchived2020-05-15 at theWayback Machine,anda considerable test suiteArchived2020-05-15 at theWayback MachineincludingBrian Wichmann's tests.Archived2020-05-15 at theWayback MachineAlso there is a rather superficialAlgol60 to Atlas Autocode source-level translatorArchived2020-05-15 at theWayback Machine.
- Eric S. Raymond'sRetrocomputing Museum,among others a link to the NASE ALGOL 60 interpreter written in C.
- The NASE interpreter
- Stories of the B5000 and People Who Were There: a dedicated ALGOL computer[1],[2]
- Bottenbruch, Hermann (1961).Structure and Use of ALGOL 60(Report).doi:10.2172/4020495.OSTI4020495.
- NUMALA Library of Numerical Procedures in ALGOL 60 developed at The Stichting Centrum Wiskunde & Informatica (legal successorof Stichting Mathematisch Centrum)legal owner.
- ALGOL 60 resources: translators, documentation, programs
- ALGOL 60included in Racket