🚀 go-pugleaf

In article <EIVERSON.90Nov12212535@thrinakia.nmsu.edu> eiverson@nmsu.edu (Eric Iverson) writes:
>
>I am in the process of writing a parser in Parlog on the Sequent
>Symmetry and am having a rather difficult time of it.  I am beginning
>to suspect that it is Parlog and not me that is at fault.  One main
>reason for this suspicion is that I typed in a parser program from
>Conlon's "Programming in Parlog" and it does *not* work.........

The Parlog parser published in Tom Conlon's book is correct, as far as
I'm aware, if not very efficient.  There is no difficulty in running it 
on a full implementation of Parlog, such as MacParlog or PC-Parlog.  The 
problem appears to be that the Parallel Parlog system (as on the Sequent)
imposes the restriction that "deep" guards, which are heavily used in
Tom's parser, must be tried sequentially, not in (or-)parallel.
The solution is to change the clause search operator to ';' in the
procedures that use deep guards.  This seems to work, though I don't
know why the original version simply fails with no error message.

Specific questions about the behaviour of the Parallel Parlog system are
best sent to Imperial College (parlog@doc.ic.ac.uk).

Steve Gregory
University of Bristol
steve@cs.bris.ac.uk