Re: ada paper critic

[Rod Haper <rhaper@houston.rr.com>]

Jeffrey Carter wrote:
> Robert A Duff wrote:
> 
>>By the way, is it true that Algol 60 and/or Algol 68 was font-sensitive
>>(i.e. "reserved words" are distinguished by being in boldface)?
> 
> 
> I've never used A68, but I knew someone who used it in the early 1980s
> who explained that keywords were somehow distinguishable from other
> identifiers. In text this difference was boldface, so calling the
> difference "font" seems as good as any. In practice, the compiler
> required the keywords to be marked somehow to indicate that they were in
> the keyword representation. I don't recall the actual details of how
> they were marked. Sorry.
> 
> Other things I recall:
> 
> The programmer could declare new infix operators. This seemed like a lot
> of work for the programmer, and no doubt for the compiler writer.
> 
> What Ada calls "type" A68 called "mode". I'm not sure what that was
> supposed to mean. "Type" seems better, though still not great, since
> usually declaring a type in Ada requires more than just the type
> declaration.
> 
> These are remarks by an ignorant non-A68 user, so weigh them
> appropriately.
> 


Ah, ALGOL 60, now that brings many very fond memories back to mind.  I 
was fortunate enough to have learned ALOGL 60 as my programming "mother 
tongue" back in the "dark ages" of 1966 on the Burrough's B5500 (a 
wonderfull machine and more very fond memories).  I still have my copy 
of "a guide to ALGOL programming" by Daniel McCracken, 1962.  It uses 
bold type to distinguish ALGOL reserved words from identifier words 
although the convention was to underline them which I recall doing in 
hand-written code.  McCracken notes that on some implementations you 
could use the same name for an identifier as an ALGOL reserved word if 
the ALGOL reserved word is set off by distinguishing marks such as 
quotes or dollar signs so that there is no confusion - ala, 'true' and 
true and $while$ and while.  I don't recall ever doing this on the B5500 
but the $ sign usage does ring a bell - aleit very faintly after all 
these years - we almost certainly would have avoided this practice.  As 
for declaring new infix operators, that must have been a part of ALGOL 
68 which, saddly, I never had an opportunity to use.

-- 
Rod

+----------------------------------+
|     There is a better way ...    |
|   LAP => Linux + Ada95 + Python  |
+----------------------------------+