🚀 go-pugleaf

russo@caip.rutgers.edu (Mark F. Russo) writes:
>
>I have a question about Quintus Prolog and the latest functionality of
>the external language interface.  I know that you can install a C
>function as a predicate call in a Quintus Prolog program.  My question
>is, can you then make a query back into the prolog database from that
>external C function.  This is currently possible using BIM_Prolog.

Your observations are correct.  Not being able to call Prolog goals
from an external language (e.g. C) is one of the few things missing
in Quintus Prolog.  The only solution until Quintus provides this
feature is to write a small interpreter that eats Prolog goals in
small pieces (atoms, integers and floats) and reconstructs the goal
in Prolog itself.  We actually use this method, although it remains
a kludge.  We previously used the IPC method, but performance then
becomes unpredictable (on Sun workstations) because of swapping.

>Are there any other prologs with which this can be done?

BIM_Prolog as you mentioned.  SWI-Prolog (contact jan@swivax.uucp)
provides a collection of C functions to construct and call goals
from C in a fashion similar to BIM_Prolog.

-- Anjo.