Compilers - Prolog and evaluating expressions

Author

Prolog and evaluating expressions

James Sison

2007-10-04, 10:10 pm

I'm trying to write this prolog interpreter but i encountered a
problem. Let's say i'm evaluating a rule and i found a possible
solution. How will i store my current position in the parse tree of
the rule if i'm going back to it when i backtrack? I'm thinking of
using a stack but then, i have no idea how to use it for this
application. Do you guys have any opinions on the matter?

Nils M Holm

2007-10-05, 7:14 pm

James Sison <the_evil_trembles@yahoo.com> wrote:
> I'm trying to write this prolog interpreter but i encountered a
> problem. Let's say i'm evaluating a rule and i found a possible
> solution. How will i store my current position in the parse tree of
> the rule if i'm going back to it when i backtrack? I'm thinking of
> using a stack but then, i have no idea how to use it for this
> application. Do you guys have any opinions on the matter?

Using a stack or, more generally, recursion is a natural solution to
this problem. It might be best to study one of the tiny Prolog
interpreters that you can find on the Web. In case you are not opposed
to Scheme/LISP, here is a very tiny one:

http://www.t3x.org/sketchy/prog/prolog.html

--
Nils M Holm <nmh@t3x.org> -- http://t3x.org/nmh/

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