Re: ALGOL - lexical analyzer

nmm1@cus.cam.ac.uk (Nick Maclaren)
7 May 2005 16:59:26 -0400

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From: nmm1@cus.cam.ac.uk (Nick Maclaren)
Newsgroups: comp.compilers
Date: 7 May 2005 16:59:26 -0400
Organization: University of Cambridge, England
References: 05-05-027 05-05-029
Keywords: lex, algol68

Nick Maclaren <nmm1@cus.cam.ac.uk> wrote:
>Eddie <edimodric@makni.inet.hr> wrote:
>>i'm looking for LEX script file for ALGOL lexical analyzer.
>
>[Algol 60 had a well-defined display representation suitable for
>printing in magazines, with keywords in boldface, but it was about 35
>years too early for computers to do that. Some implementations
>reserved the keywords, e.g. BEGIN and END which was wrong since you
>were allowed to have variables called begin and end, others did gross
>things like quoting them all, e.g., 'BEGIN' and 'END' which was
>unusable. I can't lay my hands on my Algol68 report but as I recall
>they avoided that mistake and defined it in a single ASCII-ish
>character set. -John]


The actual Algol 68 Report was in a ghastly multi-font structure,
which once had people discussing whether something was a Roman or
italic full stop :-) Most versions were in an even more ghastly
representation that used overprinting (remember that?) to emulate the
different fonts. I have one of them.


The language used a single ASCII-ish character set, as you say, but
allowed several different forms of stropping to distinguish keywords.
Some of them were almost never used, including one that allowed even
newlines within identifiers! The simplest one was case stropping,
where keywords were in upper case and identifiers in lower; I should
have to remind myself what mixed case meant.


Regards,
Nick Maclaren.


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