ABSTRACT SYNTAX NOTATION TRANSLATOR
    Contributed by C.D. Farris and P. Singleton, University of Keele
                    Received on the 25th of July 1989
                  Shelved on the 14th of November 1989


Abstract Syntax Notation is a formalism for describing language syntax.
Grammars are written as Prolog terms, and compiled into an optimised
Definite Clause Grammar.

ASN is described in "The compilation of metalanguages into Prolog", by
C.D. Farris and P. Singleton, University Computing, vol 11, no 2, pp
62-75. The article includes a listing of the code, which is what makes
up this entry.


This entry comes as the following files:
    ASN.PL      - the source.
    IO.PL       - I/O predicates I've written for portability.
    USEFUL.PL   - other predicates written for portability.
    ASN.OLD     - the original, Quintus Prolog, version.
    ASN.PRE     - this file.


To run ASN, consult ASN.PL. It consults IO and USEFUL. If using Quintus
Prolog, you can consult ASN.OLD instead. This consults several Quintus
libraries. Then call the predicates
    ?- demo1.
    ?- demo2.
    ?- demo3.
    ?- demo4.
    ?- demo5.
    ?- demo6.
to demonstrate the program.


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

    The original version used some Quintus-specific predicates, mainly
    for I/O. I have replaced these by calls to Edinburgh Prolog
    predicates, defined in IO and USEFUL.


PORTABILITY :

    Source includes % comments. There are also some long character lists
    (i.e. "..." strings) in the demo predicates which span more than one
    line. How these are denoted will be system-dependent.


INTERNAL DOCUMENTATION :

    Each predicate comes with a brief description of its purpose. The
    theory behind ASN is not described in the program, but you can get
    it from the original article.