Test code for Prolog.
It runs in Common Lisp.

Usage

Run Common Lisp.

$ sbcl
...
*

Load match.lisp.

* (load #p"match.lisp")

Use the package MATCH.

* (defpackage work (:use cl match))
* (in-package work)

Initialize match.
Run init-match or with-match.

* (init-match)

or,

* (with-match
    form
    ...)

Here is an example of execution.
The following Prolog rules are used.

aaa.
bbb(ccc, ddd).
eee(X) :- bbb(X, ddd), aaa.

In Common Lisp, it is defined as follows

(defrule aaa)
(defrule (bbb ccc ddd))
(defrule (eee ?x) (bbb ?x ddd) aaa)

Here are some examples.

* (match (bbb ccc ddd))
NIL
T

* (match (bbb ccc eee))
NIL
NIL

* (match (bbb ?x ?y))
((?X . CCC) (?Y . DDD))
T

* (match (bbb _ ?y))
((?Y . DDD))
T

This is an example of using a query.

* (defrule (append () ?x ?x))
* (defrule (append (?u . ?x) ?y (?u . ?z))
    (append ?x ?y ?z))
* (query (append ?x ?y (a b c d e f)))
?X = NIL
?Y = (A B C D E F)
(y or n) n  ;; [input]
?X = (A)
?Y = (B C D E F)
(y or n) n  ;; [input]
?X = (A B)
?Y = (C D E F)
(y or n) y  ;; [input]
((?X A B) (?Y C D E F))
T

The match macro will return the first match.
The query macro queries for matches with the y-or-n-p function.

The match-lisp function can be used to select the matching condition.

* (match-lisp
    '(append ?x ?y (a b c d e f))
    (lambda (list)
      (= 3 (length (cdr (assoc '?x list))))))
((?X A B C) (?Y D E F))
T

The following commands can be used in Prolog.

• true
• fail
• ! (cut)
• and
• or
• is
• progn

is argument is passed directly to eval in Common Lisp.

* (with-match
    (defrule (aaa 100))
    (query (aaa ?x) (is ?y (+ 200 ?x))))
?X = 100
?Y = 300
(y or n)

progn returns the result of eval in Common Lisp.
For example, use the following.

* (defrule (< ?x ?y) (progn (< ?x ?y)))
* (match (< 10 20))
NIL
T

License

The Unlicense

Distribution

https://github.com/nptcl/match