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  • Algol 68 - lexical rules for identifiers

    From Janis Papanagnou@[email protected] to comp.lang.misc on Mon Feb 23 19:29:54 2026
    From Newsgroup: comp.lang.misc

    Standard identifiers in Algol 68 may contain arbitrary spaces,
    besides 'intlengths', 'int lengths', or even 'in tl en gt hs'.

    I've found in some old editor syntax file Algol 68 identifiers
    defined with underscores in their name, like 'int_lengths'.

    This syntax variant is not supported by the Genie interpreter,
    but I'm interested to know whether other compiler/interpreter
    support such a lexical variant.

    Janis

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  • From Andy Walker@[email protected] to comp.lang.misc on Tue Feb 24 13:37:57 2026
    From Newsgroup: comp.lang.misc

    On 23/02/2026 18:29, Janis Papanagnou wrote:
    I've found in some old editor syntax file Algol 68 identifiers
    defined with underscores in their name, like 'int_lengths'.
    This syntax variant is not supported by the Genie interpreter,
    but I'm interested to know whether other compiler/interpreter
    support such a lexical variant.

    I don't know of any [I think A68R didn't allow it], but
    perhaps worth noting that "_" is a natural choice for "letter
    aleph" -- that is, part of an identifier [or mode/operator name]
    that the language knows about but that ordinary source code has
    no way of writing. There are lots of examples in the RR, notably
    in the library routines and similar. You may perhaps find further
    info in the reports of the Stillwater [Oklahoma] Conference, which
    ISTR had a lot of papers on "worthy" characters and the like [but
    I don't have a copy myself].

    Andy
    --
    Andy Walker, Nottingham.
    Andy's music pages: www.cuboid.me.uk/andy/Music
    Composer of the day: www.cuboid.me.uk/andy/Music/Composers/Schulz-Evler
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  • From Janis Papanagnou@[email protected] to comp.lang.misc on Wed Feb 25 06:42:13 2026
    From Newsgroup: comp.lang.misc

    On 2026-02-24 14:37, Andy Walker wrote:
    On 23/02/2026 18:29, Janis Papanagnou wrote:
    I've found in some old editor syntax file Algol 68 identifiers
    defined with underscores in their name, like 'int_lengths'.
    This syntax variant is not supported by the Genie interpreter,
    but I'm interested to know whether other compiler/interpreter
    support such a lexical variant.

        I don't know of any [I think A68R didn't allow it], but
    perhaps worth noting that "_" is a natural choice for "letter
    aleph" -- that is, part of an identifier [or mode/operator name]
    that the language knows about but that ordinary source code has
    no way of writing.  There are lots of examples in the RR, notably
    in the library routines and similar.  You may perhaps find further
    info in the reports of the Stillwater [Oklahoma] Conference, which
    ISTR had a lot of papers on "worthy" characters and the like [but
    I don't have a copy myself].

    Thanks. - I think it should be fairly safe to remove all underscores
    from the syntax file's standard prelude identifiers then.


    The "unworthy characters" that you mention is another thing. I think
    I had tested whether those alternative symbols (like 'NE' represented
    as a single character symbol) will be accepted by Genie, but no; all
    UTF-8 characters seem to be considered "unworthy"? I don't quite get
    it who determines what's considered "worthy" or "unworthy", the Genie
    or the Standard. I also wonder about all those alternative characters
    that can be seen in old Algol 68 books, from the days where no UTF-8
    (or Unicode) was existing.

    Janis

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