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| From | Andy Walker <anw@cuboid.co.uk> |
|---|---|
| Newsgroups | comp.lang.misc |
| Subject | Re: Algol 68 - to be or not to be a Local Range |
| Date | 2025-12-22 17:35 +0000 |
| Organization | Not very much |
| Message-ID | <10ibvg7$3cquk$1@dont-email.me> (permalink) |
| References | <10i64p2$16li1$1@dont-email.me> <10i6a7n$1rcgi$1@dont-email.me> <10i6jge$16li1$2@dont-email.me> |
On 20/12/2025 16:39, Janis Papanagnou wrote:
[re "LOC" inside loops:]
> Re "A68G"; actually (AFAICT) that's not a Genie issue. I found that
> property explicitly described and with a similar example in
> Lindsey, van der Meulen: "Informal Introduction to ALGOL 68" [*]
Hmm. You seem to be correct. "FOR i ..." seems to be a local
definition of "i", but technically not a declaration, so that a few
weasel words later, you get the effect you describe. So in deeply nested
loops you can have arbitrarily many copies of values with the same
identifier. This is pretty yucky, IMO, and also breaks the equivalence
of loops with "the same" code written out using jumps and explicit tests
[as described in the RR].
> (If I understand correctly that's an informal amendment to the RR?)
No, it's supposed to be an informal description of A68, readable
by people who don't understand two-level grammars. Technically, there
can be no amendments to the RR. The Cttee hath spoken! The most you can
claim is that there are typos, so that the editor of Algol Bulleting can
report imperfections in the copying process that produced paper copies of
the RR. I fear that's the sort of thing that gave A68 a bad name. There
were enough errors [I found and reported half a dozen] that an updated RR
would not have been a bad thing,
--
Andy Walker, Nottingham.
Andy's music pages: www.cuboid.me.uk/andy/Music
Composer of the day: www.cuboid.me.uk/andy/Music/Composers/Hummel
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Algol 68 - to be or not to be a Local Range Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2025-12-20 13:28 +0100
Re: Algol 68 - to be or not to be a Local Range Andy Walker <anw@cuboid.co.uk> - 2025-12-20 14:01 +0000
Re: Algol 68 - to be or not to be a Local Range Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2025-12-20 17:39 +0100
Re: Algol 68 - to be or not to be a Local Range Andy Walker <anw@cuboid.co.uk> - 2025-12-22 17:35 +0000
Re: Algol 68 - to be or not to be a Local Range Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2025-12-22 19:10 +0100
Re: Algol 68 - to be or not to be a Local Range Lawrence D’Oliveiro <ldo@nz.invalid> - 2025-12-22 21:17 +0000
Re: Algol 68 - to be or not to be a Local Range Lawrence D’Oliveiro <ldo@nz.invalid> - 2025-12-21 01:59 +0000
Re: Algol 68 - to be or not to be a Local Range Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2025-12-21 05:47 +0100
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