Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!uwm.edu!linac!att!ucbvax!physics.oxford.ac.uk!HALLAM
From: HALLAM@physics.oxford.ac.uk ("Phillip M. Hallam-Baker")
Newsgroups: comp.sys.transputer
Subject: RE Anarchic Protocol ANY (occam2)
Message-ID: <29382.9105161115@prg.oxford.ac.uk>
Date: 16 May 91 12:14:00 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 36


Luiz Felipe Perrone's problem with CHAN OF ANY would appear to be due to
the fact that internal and external channels are handled differently.

(yes yes yes i know it's the same instruction blah blah blah....)

Data sent on external chanels is reduced to a bit stream. The atomic unit is
the byte. Data sent on internal channels is moved using a block move
the atomic unit is a label. 

Thus

CHAN OF ANY fred

PAR
  fred ! 1 ; 2
  [2]INT array :
  fred ? array

will only work when fred is placed on an exernal channel.

This is not an error in the occam implementation. CHAN OF ANY is there for
cases where there is a need to "play dirty"

However Luiz's original problem was entirely reasonable. Occam just dosen't
handle records and in the real world records are what the punters need. I
know you can fiddle arround with aliases IS RETYPES etc but this is messy.
There are also performance implications - the code produced by the D605 toolkit 
is quite wierd, and does not perform a large number of obvious optimisations.

It would be nice to have a stripped down version of occam with a more
usable typing mechanism which would handle records. This should be integrated
to the channel PROTOCOL declarations.


		Phill Hallam-Baker