STRUCTURES IN PROLOG
                           By Jean G. Vaucher,
     De'partement d' informatique et R.O., Universite' de Montre'al
                   Shelved on the 15th of August 1989


This package is taken from

    "Record manipulation in Prolog" (Short Communication),
    Jean G. Vaucher,
    De'partement d' informatique et R.O., Universite' de Montre'al.

    in

    "Software - Practice and Experience",
    Vol _19_(8),
    pp. 801-807,
    (August 1989).

It provides a  set of primitive predicates and operators  that allow the
arguments  of Prolog  structures  to  be accessed  by  name rather  than
position, and  that implement Lisp-style  property lists. These  make it
more  convenient  to  write  programs that  are  easily  understood  and
modified. [JNP]


Examples:
---------

    ?- def_record( person(name,age,address) ).
    Define a template for the 'person' structure.

    ?- inst( person, P ),
       field( P..name, 'Matthew Latner Linton' ),
       field( P..name, Z ).
    Create a 'person' in P, set its name, and unify that name with Z.

    ?- def_record( address(number,street,town) ).
    Template for the 'address' structure.

    ?- inst( address, A ),
       inst( person, P ),
       field( P..address, A ),
       field( P..age, 25 ),
       field( P..address..street, 'St. Peter's Street' ).
       field( P..address..town, 'Hanningtown' ).
    Create an address A and person P, and set some fields.

    ?- inst( person, P ),
       field( P..name, 'Fred' ), field( P..age, 25 ),
       update( P..name, 'Bert', P2 ).
    Create a person, and use 'update' to make a modified copy.



SIZE : 18 kilobytes.


CHECKED ON EDINBURGH-COMPATIBLE (POPLOG) PROLOG : yes.


PORTABILITY : Easy.


INTERNAL DOCUMENTATION :

    Long  description  of  how  to  use  the  predicates,  and  a  brief
    description of how they work: adequate given their simplicity.