Re: [HM] The sign ":="

Michael S. Mahoney (MIKE@PUCC.PRINCETON.EDU)
Mon, 19 Oct 98 14:41:36 EDT

By his own testimony ("Recollections about the development of Pascal",
in _History of Programming Languages II_, ed. Bergin and Gibson [ACM
Press, 1996], Chap. III), Wirth did not join WG2.1 until 1964, when it
was engaged in extending Algol 60. He was not a member of the Algol 60
group, nor did he play a role in the Algol 60 report, which was published
in 1960 and in a revised version in 1963 (see _History of Programming
Languages_, ed. Wexelblat [ACM Press, 1981], Chap. III).

Wirth's article suggests that he views Pascal as much more than a
"revised version of ALGOL60".

Mike Mahoney

o=o=o=o=o=o=o=o=o=o=o=o=o=o=o=o=o=o=o=o=o=o=o=o=o=o=o=o=o=o=o=o=o=o=o=
Michael S. Mahoney Department of History Princeton University
mike@princeton.edu 303 Dickinson Hall Princeton, NJ 08544
phone 609-258-4157 fax 609-258-5326
WWW Home Page http://www.princeton.edu/~mike
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----------------------------Original message----------------------------
>
>The first usage known to me was by Wirth, the inventor of the Pascal
>programming language, some time during the 1970's.
>
>Roger Cooke
>

I wrote in a previous contribution:

>
>The sign comes from the ALGOL60 programming language
>(1960) and means in say ``$i := j+1$'' that the variable i
>gets assigned the value in variable j plus 1.
>
>Since this is similar to definitions (theoretical) computer
>scientists have started to use it that way.
>

Cooke's remark gets explained by the fact that Wirth's Pascal
programming language is a modified version of ALGOL60. In fact,
Wirth was also one of the 10-15 scientists of the WorkGroup
WG2.1 of IFIP developing the standard ALGOL60 language and writing
the defining document "the ALGOL60 Report" in 1960.