Re: Process Placement in Occam 2.1

[tjoccam@xxxxxxxxxxx]

A couple more connected questions...

> Kai,
>
> On 11/03/2006 14:24, Koehne Kai wrote:
>> I have a specific question concerning the Occam 2.1 standard. The
>> question is if this is legal occam:
>>
>> SEQ
>>   PROCESSOR 1              -- PROCESSOR outside PLACED PAR!!
>>     SKIP
>>   SKIP
>
> My belief is that it is not; it doesn't really make sense.  The compiler
> would have to invent a baton-passing event (which you could yourself, of
> course, to achieve the effect), and that is contrary to the WYSIWIG
> philosophy of occam.  The configuration language for deploying occam
> programs was a bit of a bolt-on; PLACED PAR is the only component that
> intrudes into the language proper.

I never used PLACED PAR, only the configuration language. My impression
was that PLACED PAR was an "old" form that got replaced by the
configuration language, and that with the configuration language
available, good practice was to avoid it entirely. Any comments?

>
>> The BNF grammar that is part of the standard allows it:
>>
>> parallel     = ...
>>                 | placedpar
>>
>> placedpar = PLACED PAR
>>                     { placedbar }
>>                 | PLACED PAR replicator
>>                     placedpar
>>                 | PROCESSOR expression
>>                     process
>>
>> process    = ...
>>                 | parallel
>>                 | ...
>
> That just looks like laziness in drawing up the grammar, avoiding
> repeating
> the constructor forms in both "outer" and "nested" context.  I don't have
> a
> copy to hand; does it treat the productions for IF and ALT differently?

Is there any version of the occam syntax that avoids this "laziness in
drawing up the grammar"? Has anyone done a critical study of it to clean
up these points?

In section G (Syntax Summary) of the Inmos occam 2 Reference Manual
(Prentice Hall, 1988), it interposes "construction" between "process" and
"parallel".

Larry Dickson

>
> Best,
> --
> M
>
>