ALGOL 60

ALGOL 60 – with COBOL – were the first languages to seek standardization.

• [http://www.iso.org/iso/home/store/catalogue_tc/catalogue_detail.htm?csnumber=6126 ISO 1538:1984] Programming languages – ALGOL 60 (stabilized)
• [http://www.iso.org/iso/home/store/catalogue_tc/catalogue_detail.htm?csnumber=6286 ISO/TR 1672:1977] Hardware representation of ALGOL basic symbols ... (now withdrawn)

ALGOL 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 standard input/output facilities 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 Backus developed the Backus normal form method of describing programming languages specifically for ALGOL 58. It was revised and expanded by Peter Naur for ALGOL 60, and at Donald Knuth's suggestion renamed Backus–Naur form.{{cite journal |last=Knuth |first=Donald E. |author-link=Donald Knuth |title=Backus normal Form vs Backus Naur Form |journal=Communications of the ACM |volume=7 |issue=12 |pages=735–6 |date=December 1964 |doi=10.1145/355588.365140 |s2cid=47537431|doi-access=free }}

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."[http://awards.acm.org/citation.cfm?id=1024454&srt=all&aw=140&ao=AMTURING&yr=2005 ACM Award Citation / Peter Naur], 2005

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, and Michael Woodger (from Europe)
• John Warner Backus, Julien Green, Charles Katz, John McCarthy, Alan Jay Perlis, and Joseph 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 include recursion. It was inserted into the specification at the last minute, against the wishes of some of the committee.{{cite web|url=https://vanemden.wordpress.com/2014/06/18/how-recursion-got-into-programming-a-comedy-of-errors-3/|title=How recursion got into programming: a tale of intrigue, betrayal, and advanced programming-language semantics|first=Maarten|last=van Emden|date=2014|series=A Programmer's Place}}

ALGOL 60 inspired many languages that followed it. Tony Hoare remarked: "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."{{cite web |last=Hoare |first=C.A.R. |author-link=Tony Hoare |title=Hints on Programming Language Design |date=December 1973 |url=http://www.eecs.umich.edu/~bchandra/courses/papers/Hoare_Hints.pdf |page=27}} (This statement is sometimes erroneously attributed to Edsger W. Dijkstra, also involved in implementing the first ALGOL 60 compiler.){{cite web |last1=Abelson |first1=Hal |author1-link=Hal Abelson |last2=Dybvig |first2=R. K. |author2-link=R. Kent Dybvig |editor1-last=Rees |editor1-first=Jonathan |editor2-last=Clinger |editor2-first=William |title=Revised(3) Report on the Algorithmic Language Scheme (Dedicated to the Memory of ALGOL 60)

|url=http://groups.csail.mit.edu/mac/ftpdir/scheme-reports/r3rs-html/r3rs_toc.html

|access-date=2009-10-20

|display-authors=etal}}

To date there have been at least 70 augmentations, extensions, derivations and sublanguages of ALGOL 60.[http://hopl.murdoch.edu.au/showlanguage.prx?exp=1807 The Encyclopedia of Computer Languages] {{webarchive |url=https://web.archive.org/web/20110927014141/http://hopl.murdoch.edu.au/showlanguage.prx?exp=1807 |date=September 27, 2011}}

The Burroughs dialects included special system programming dialects such as ESPOL and NEWP.

ALGOL 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 of transput (ALGOL 68 parlance for input/output) facilities.

ALGOL 60 provided two evaluation strategies for parameter passing: the common call-by-value, and call-by-name. The procedure declaration specified, for each formal parameter, which was to be used: value specified for call-by-value, and omitted for call-by-name. Call-by-name has certain effects in contrast to call-by-reference. For example, without specifying the parameters as value or reference, 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.{{cite book |last1=Aho |first1=Alfred V. |author1-link=Alfred V. Aho |last2=Sethi |first2=Ravi |author2-link=Ravi Sethi |last3=Ullman |first3=Jeffrey D. |author3-link=Jeffrey Ullman |year=1986 |title=Compilers: Principles, Techniques, and Tools |edition=1st |publisher=Addison-Wesley |isbn=978-0-201-10194-2 |title-link=Dragon Book (computer science)}}, Section 7.5, and references therein 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 Knuth devised the "man or boy test" to separate compilers that correctly implemented "recursion and non-local references." This test contains an example of call-by-name.

The ALGOL 60 reports recognize three different levels of language, i.e., a Reference Language, a Publication Language, and several Hardware Representations. The Reference and Publication languages have no reserved words, however the reports do recommend{{Harvnb|Naur et al.|1963|loc=3.2.4. Standard functions}}

reserving some identifiers for standard functions.

The reports briefly describe hardware representations. Implementations differ in their hardware representations of underlined independent basic symbols{{Harvnb |Naur et al. |1963 |loc=2.1. Letters}}: (1) It should be particularly noted that throughout the reference language underlining [here this looks like underlined; N.L.] is used for defining independent basic symbols (see sections 2.2.2 and 2.3). These are understood to have no relation to the individual letters of which they are composed. Within the present report underlining will be used for no other purposes.

1. Reserved words
2. Stropping

There are 24 reserved words in the Modified Report:

{{div col|colwidth=7em}}

• ARRAY
• BEGIN
• BOOLEAN
• COMMENT
• DO
• ELSE
• END
• FALSE
• FOR
• GOTO
• IF
• INTEGER
• LABEL
• OWN
• PROCEDURE
• REAL
• STEP
• STRING
• SWITCH
• THEN
• TRUE
• UNTIL
• VALUE
• WHILE

{{div col end}}There are 35 such reserved words in the standard Burroughs Large Systems sub-language:

{{div col|colwidth=7em}}

• ALPHA
• ARRAY
• BEGIN
• BOOLEAN
• COMMENT
• CONTINUE
• DIRECT
• DO
• DOUBLE
• ELSE
• END
• EVENT
• FALSE
• FILE
• FOR
• FORMAT
• GO
• IF
• INTEGER
• LABEL
• LIST
• LONG
• OWN
• POINTER
• PROCEDURE
• REAL
• STEP
• SWITCH
• TASK
• THEN
• TRUE
• UNTIL
• VALUE
• WHILE
• ZIP

{{div col end}}

There are 71 such restricted identifiers in the standard Burroughs Large Systems sub-language:

{{div col|colwidth=7em}}

• ACCEPT
• AND
• ATTACH
• BY
• CALL
• CASE
• CAUSE
• CLOSE
• DEALLOCATE
• DEFINE
• DETACH
• DISABLE
• DISPLAY
• DIV
• DUMP
• ENABLE
• EQL
• EQV
• EXCHANGE
• EXTERNAL
• FILL
• FORWARD
• GEQ
• GTR
• IMP
• IN
• INTERRUPT
• IS
• LB
• LEQ
• LIBERATE
• LINE
• LOCK
• LSS
• MERGE
• MOD
• MONITOR
• MUX
• NEQ
• NO
• NOT
• ON
• OPEN
• OR
• OUT
• PICTURE
• PROCESS
• PROCURE
• PROGRAMDUMP
• RB
• READ
• RELEASE
• REPLACE
• RESET
• RESIZE
• REWIND
• RUN
• SCAN
• SEEK
• SET
• SKIP
• SORT
• SPACE
• SWAP
• THRU
• TIMES
• TO
• WAIT
• WHEN
• WITH
• WRITE

{{div col end}}

and also the names of all the intrinsic functions.

procedure Absmax(a) Size:(n, m) Result:(y) Subscripts:(i, k);

value n, m; array a; integer n, m, i, k; real y;

comment The 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

integer p, q;

y := 0; i := k := 1;

for p := 1 step 1 until n do

for q := 1 step 1 until m do

if abs(a[p, q]) > y then

begin y := abs(a[p, q]);

i := p; k := q

end

end Absmax;

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 of integer, above, thereby designating it as a special keyword.

Following is an example of how to produce a table using Elliott 803 ALGOL:[http://www.billp.org/ccs/A104/ "803 ALGOL"], the manual for Elliott 803 ALGOL

FLOATING POINT ALGOL TEST'

BEGIN REAL A,B,C,D'

READ D'

FOR A:= 0.0 STEP D UNTIL 6.3 DO

BEGIN

PRINT {{abbr|PUNCH(3)|sends output to the teleprinter rather than the tape punch.}},££L??'

B := SIN(A)'

C := COS(A)'

PRINT {{abbr|PUNCH(3)|sends output to the teleprinter rather than the tape punch.}},{{abbr|SAMELINE|suppresses the carriage return + line feed normally printed between arguments.}},{{abbr|ALIGNED(1,6)|controls the format of the output with 1 digit before and 6 after the decimal point.}},A,B,C'

END'

END'

Since ALGOL 60 had no I/O facilities, there is no portable hello world program in 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{{cite web |url=http://www.engin.umd.umich.edu/CIS/course.des/cis400/ |title=The ALGOL Programming Language |website=www.engin.umd.umich.edu |access-date=11 January 2022 |archive-url=https://web.archive.org/web/20100210185248/http://www.engin.umd.umich.edu/CIS/course.des/cis400/algol/algol.html |archive-date=10 February 2010 |url-status=dead}} at the University of Michigan-Dearborn Computer and Information

Science Department Hello world! ALGOL Example Program page.{{cite web |url=http://www.engin.umd.umich.edu/CIS/course.des/cis400/algol/hworld.html |title=Hello world! Example Program |website=www.engin.umd.umich.edu |access-date=11 January 2022 |archive-url=https://web.archive.org/web/20100204112923/http://www.engin.umd.umich.edu/CIS/course.des/cis400/algol/hworld.html |archive-date=4 February 2010 |url-status=dead}}

BEGIN

FILE F(KIND=REMOTE);

EBCDIC ARRAY E[0:11];

REPLACE E BY "HELLO WORLD!";

WRITE(F, *, E);

END.

Where * etc. represented a format specification as used in FORTRAN, e.g.Fortran#"Hello, World!" example

A simpler program using an inline format:

{{sxhl|2=m2|1=

BEGIN

FILE F(KIND=REMOTE);

WRITE(F, <"HELLO WORLD!">);

END.

}}

An even simpler program using the Display statement:

{{sxhl|2=m2|1= BEGIN DISPLAY("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 {{color box|rgba(255,255,255,0)|border=silver| ‘}} and {{color box|rgba(255,255,255,0)|border=silver| ’}}.

{{sxhl|2=pascal|1=

program HiFolks;

begin

print ‘Hello world’

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'

The ICT 1900 series Algol 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 %.{{cite web|url=http://www.icl1900.co.uk/techpub/tp3340.djvu|title=ICL 1900 series: Algol Language|publisher=ICL Technical Publication 3340|year=1965}}

'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 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.

{{div col |colwidth=15em}}

• ABC ALGOL
• ALGOL
• ALGOL 58
• ALGOL N
• ALGOL 68
• ALGOL W
• ALGOL X
• Atlas Autocode
• Coral 66
• Edinburgh IMP
• Jensen's Device
• ISWIM
• JOVIAL
• NELIAC
• Simula
• S-algol
• Scheme (programming language)

{{div col end}}

{{reflist|30em}}

{{refbegin}}

• {{cite journal

| journal = Communications of the ACM

| volume = 6

| issue = 1

| date = January 1963

| title = Revised Report on the Algorithmic Language Algol 60

| editor = Peter Naur

| editor-link = Peter Naur

| last1 = Backus

| first1 = John W.

| author-link1 = John Backus

| last2 = Bauer

| first2 = Friedrich L.

| author-link2 = Friedrich L. Bauer

| last3 = Green

| first3 = J.

| last4 = Katz

| first4 = C.

| author5 = J. McCarthy

| author-link5 = John McCarthy (computer scientist)

| author6 = P. Naur

| author-link6 = Peter Naur

| author7 = A.J. Perlis

| author-link7 = Alan Perlis

| author8 = H. Rutishauser

| author-link8 = Heinz Rutishauser

| author9 = K. Samuelson

| author10 = B. Vauquois

| author-link10 = Bernard Vauquois

| author11 = J.H. Wegstein

| author-link11 = Joseph Henry Wegstein

| author12 = A. van Wijngaarden

| author-link12 = Adriaan van Wijngaarden

| author13 = M. Woodger

| author-link13 = Mike Woodger

| url = https://doi.org/10.1145/366193.366201

| publisher = Association for Computing Machinery

| doi = 10.1145/366193.366201

| s2cid = 7853511

| ref = {{harvid|Naur et al.|1963}}

}}

• {{cite book |last=Kurtz |first=Thomas E. |year=1978 |chapter=BASIC |title=History of programming languages |doi=10.1145/800025.1198404 |doi-access=free |pages=515–537 |isbn=0127450408}}

{{refend}}

• {{cite tech report |last=Dijkstra |first=Edsger W. |author-link=Edsger Dijkstra |year=1961 |title="ALGOL 60 Translation: An ALGOL 60 Translator for the X1 and Making a Translator for ALGOL 60 |institution=Mathematisch Centrum |location=Amsterdam|number=35 |url=http://www.cs.utexas.edu/users/EWD/MCReps/MR35.PDF |format=PDF}}
• {{cite book |last1=Randell |first1=Brian |author1-link=Brian Randell |last2=Russell |first2=Lawford John |title=ALGOL 60 Implementation: The Translation and Use of ALGOL 60 Programs on a Computer |publisher=Academic Press |year=1964 |oclc=526731 |url=https://archive.org/details/algol60implement00rand |url-access=registration}} The design of the Whetstone Compiler. One of the early published descriptions of implementing a compiler. See the related papers: [http://www.cs.ncl.ac.uk/research/pubs/articles/papers/427.pdf Whetstone Algol Revisited], and [https://web.archive.org/web/20100525044658/http://www.cs.ncl.ac.uk/publications/books/papers/124.pdf The Whetstone KDF9 ALGOL Translator] by Brian Randell
• {{cite book |title=Geschichte der deutschsprachigen Informatik - Programmiersprachen und Übersetzerbau |language=de |trans-title=History of informatics in German-speaking countries - Programming languages and compiler design |author-first=Gerhard |author-last=Goos |author-link=:de:Gerhard Goos |publisher=Fakultät für Informatik, Karlsruhe Institute of Technology (KIT) |publication-place=Karlsruhe, Germany |date=2017-08-07 |url=http://www.kps2017.uni-jena.de/proceedings/kps2017_submission_1.pdf |access-date=2022-11-14 |url-status=live |archive-url=https://web.archive.org/web/20220519131116/http://www.kps2017.uni-jena.de/proceedings/kps2017_submission_1.pdf |archive-date=2022-05-19}} (11 pages)

• [http://www.masswerk.at/algol60/report.htm Revised Report on the Algorithmic Language ALGOL 60] by Peter Naur, et al. ALGOL definition
• A BNF [http://blackbox.userweb.mwn.de/Algol-BNF.html syntax summary] of ALGOL 60
• [https://web.archive.org/web/20111110061442/http://thor.cs.ucsb.edu/~ravenben/papers/coreos/Hoa81.pdf "The Emperor's Old Clothes"] – Hoare's 1980 ACM Turing Award speech, which discusses ALGOL history and his involvement
• [https://www.gnu.org/software/marst/ MARST], a free ALGOL-to-C translator
• [http://rogerdmoore.ca/JOUR/ An Implementation of ALGOL 60 for the FP6000] {{Webarchive|url=https://web.archive.org/web/20200725025218/http://rogerdmoore.ca/JOUR/ |date=2020-07-25}} Discussion of some implementation issues.
• {{cite journal |first=Peter |last=Naur |author-link=Peter Naur |title=The European Side of the Last Phase of the Development of ALGOL 60 |journal=ACM SIGPLAN Notices |volume=13 |issue=8 |pages=15–44 |date=August 1978 |doi=10.1145/960118.808370 |s2cid=15552479 |url=http://portal.acm.org/ft_gateway.cfm?id=808370|url-access=subscription }}
• 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 the [http://history.dcs.ed.ac.uk/archive/os/emas/users/ercc07/emas-2900/algolps9.txt BNF for Algol60] {{Webarchive|url=https://web.archive.org/web/20200515185211/http://history.dcs.ed.ac.uk/archive/os/emas/users/ercc07/emas-2900/algolps9.txt |date=2020-05-15}} and the [http://history.dcs.ed.ac.uk/archive/os/emas/emas2/compilers/algol/algol60fs.imp.html ICL2900 compiler source] {{Webarchive|url=https://web.archive.org/web/20200515190532/http://history.dcs.ed.ac.uk/archive/os/emas/emas2/compilers/algol/algol60fs.imp.html |date=2020-05-15}}, [http://history.dcs.ed.ac.uk/archive/os/emas/emas2/compilers/algol/bsyslib.txt-view.html library documentation] {{Webarchive|url=https://web.archive.org/web/20200515190530/http://history.dcs.ed.ac.uk/archive/os/emas/emas2/compilers/algol/bsyslib.txt-view.html |date=2020-05-15}}, and [http://history.dcs.ed.ac.uk/archive/os/emas/users/ercc07/emas-2900/ a considerable test suite] {{Webarchive|url=https://web.archive.org/web/20200515175751/http://history.dcs.ed.ac.uk/archive/os/emas/users/ercc07/emas-2900/ |date=2020-05-15}} including [http://history.dcs.ed.ac.uk/archive/os/emas/users/ercc07/emas-2900/wichtests_pete1.txt Brian Wichmann's tests.] {{Webarchive|url=https://web.archive.org/web/20200515185136/http://history.dcs.ed.ac.uk/archive/os/emas/users/ercc07/emas-2900/wichtests_pete1.txt |date=2020-05-15}} Also there is a rather superficial [http://history.dcs.ed.ac.uk/archive/os/emas/users/ercc07/emas-2900/palgcons.txt Algol60 to Atlas Autocode source-level translator] {{Webarchive|url=https://web.archive.org/web/20200515185142/http://history.dcs.ed.ac.uk/archive/os/emas/users/ercc07/emas-2900/palgcons.txt |date=2020-05-15}}.
• Eric S. Raymond's [http://www.catb.org/retro/ Retrocomputing Museum], among others a link to the NASE ALGOL 60 interpreter written in C.
• [http://www.bertnase.de/a60 The NASE interpreter]
• Stories of the B5000 and People Who Were There: a dedicated ALGOL computer [http://ed-thelen.org/comp-hist/B5000-AlgolRWaychoff.html], [http://archive.computerhistory.org/resources/text/Knuth_Don_X4100/PDF_index/k-8-pdf/k-8-u2779-B5000-People.pdf]
• {{cite report |last=Bottenbruch |first=Hermann |year=1961 |title=Structure and Use of ALGOL 60 |doi=10.2172/4020495 |osti=4020495 |url=https://digital.library.unt.edu/ark:/67531/metadc871723/|doi-access=free }}
• [http://www.softwarepreservation.org/projects/ALGOL/source/numal NUMAL] A Library of Numerical Procedures in ALGOL 60 developed at The Stichting Centrum Wiskunde & Informatica (legal successor of Stichting Mathematisch Centrum) [https://web.archive.org/web/20101005121036/http://www.cwi.nl/en/general/Address legal owner].
• [http://www.algol60.org ALGOL 60 resources: translators, documentation, programs]
• [https://docs.racket-lang.org/algol60/ ALGOL 60] included in Racket

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