Re: Closing keywords (was Re: Algol, and language design)

In article <1990Aug10.035630.764@esegue.segue.boston.ma.us>, writes:
> As far as the syntax is concerned, Modula deviates from its ancestor
> Pascal in an essential respect: statement structures consistently
> follow a single guiding rule. Every structured statement begins with
> a keyword (uniquely identifying the kind of structure) and ends
> with a closing symbol.


The curious thing about this is that Pascal was designed at least in part
as a reaction *against* Algol 68, in which the "arms" of structured
statements were "serial clauses" and each structured statement had its own
kind of terminator. Well, sort of. You could always use ( and ), so


begin s1; ...; sn end
=> ( s1; ...; sn )
if c1 then t1 elif c2 then t2 ... else f fi
            => ( c1 | t1 |: c2 | t2 ... | f )
case c in s1, s2, ..., sn out f esac
              => ( c | s1, s2, ..., sn | f )


though you couldn't use (..) for loops. So Modula syntax was a reversion
to the Algol 68 approach.


Does anyone know where the idea came from in Algol 68? Did Wirth ever
say why Pascal didn't imitate _that_ aspect of its distinguished predecessor?
--
[It is my impression that Algol68 sprang more or less whole from Van
Wijngaarden's (I hope that's right) brain, but I haven't dug into its
history in any detail. There is lots of great stuff in Algol68 that is
slowly being rediscovered; any student of programming languages should look
at it. -John]
--

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