  pmatch , a simple matcher

  Copyright ( C ) 2009 , 2010 , 2012 Free Software Foundation , Inc
  Copyright ( C ) 2005,2006,2007  
  Copyright ( C ) 2007   
;;;
;;; This library is free software; you can redistribute it and/or
;;; modify it under the terms of the GNU Lesser General Public
  License as published by the Free Software Foundation ; either
  version 3 of the License , or ( at your option ) any later version .
;;;
;;; This library is distributed in the hope that it will be useful,
;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
;;; Lesser General Public License for more details.
;;;
  You should have received a copy of the GNU Lesser General Public
;;; License along with this library; if not, write to the Free Software
  Foundation , Inc. , 51 Franklin Street , Fifth Floor , Boston ,     USA

  Originally written by   for LeanTAP in Kanren , which is
  available under the MIT license .
;;;
;;; 
;;;
;;; This version taken from:
  αKanren : A Fresh Name in Nominal Logic Programming
  by    and   
  Proceedings of the 2007 Workshop on Scheme and Functional Programming
  Université Laval Technical Report DIUL - RT-0701

  To be clear : the original code is MIT - licensed , and the modifications
  made to it by  are under  's license ( currently LGPL v3 + ) .

;;; Code:

(define-module (system base pmatch)
  #:export-syntax (pmatch))

(define-syntax-rule (pmatch e cs ...)
  (let ((v e)) (pmatch1 v cs ...)))

(define-syntax pmatch1
  (syntax-rules (else guard)
    ((_ v) (if #f #f))
    ((_ v (else e0 e ...)) (let () e0 e ...))
    ((_ v (pat (guard g ...) e0 e ...) cs ...)
     (let ((fk (lambda () (pmatch1 v cs ...))))
       (ppat v pat
             (if (and g ...) (let () e0 e ...) (fk))
             (fk))))
    ((_ v (pat e0 e ...) cs ...)
     (let ((fk (lambda () (pmatch1 v cs ...))))
       (ppat v pat (let () e0 e ...) (fk))))))

(define-syntax ppat
  (syntax-rules (_ quote unquote)
    ((_ v _ kt kf) kt)
    ((_ v () kt kf) (if (null? v) kt kf))
    ((_ v (quote lit) kt kf)
     (if (equal? v (quote lit)) kt kf))
    ((_ v (unquote var) kt kf) (let ((var v)) kt))
    ((_ v (x . y) kt kf)
     (if (pair? v)
         (let ((vx (car v)) (vy (cdr v)))
           (ppat vx x (ppat vy y kt kf) kf))
         kf))
    ((_ v lit kt kf) (if (eq? v (quote lit)) kt kf))))


 This library is free software; you can redistribute it and/or
 modify it under the terms of the GNU Lesser General Public
 either

 This library is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 Lesser General Public License for more details.

 License along with this library; if not, write to the Free Software

 

 This version taken from:
 Code:
  pmatch , a simple matcher

  Copyright ( C ) 2009 , 2010 , 2012 Free Software Foundation , Inc
  Copyright ( C ) 2005,2006,2007  
  Copyright ( C ) 2007   
  version 3 of the License , or ( at your option ) any later version .
  You should have received a copy of the GNU Lesser General Public
  Foundation , Inc. , 51 Franklin Street , Fifth Floor , Boston ,     USA

  Originally written by   for LeanTAP in Kanren , which is
  available under the MIT license .
  αKanren : A Fresh Name in Nominal Logic Programming
  by    and   
  Proceedings of the 2007 Workshop on Scheme and Functional Programming
  Université Laval Technical Report DIUL - RT-0701

  To be clear : the original code is MIT - licensed , and the modifications
  made to it by  are under  's license ( currently LGPL v3 + ) .


(define-module (system base pmatch)
  #:export-syntax (pmatch))

(define-syntax-rule (pmatch e cs ...)
  (let ((v e)) (pmatch1 v cs ...)))

(define-syntax pmatch1
  (syntax-rules (else guard)
    ((_ v) (if #f #f))
    ((_ v (else e0 e ...)) (let () e0 e ...))
    ((_ v (pat (guard g ...) e0 e ...) cs ...)
     (let ((fk (lambda () (pmatch1 v cs ...))))
       (ppat v pat
             (if (and g ...) (let () e0 e ...) (fk))
             (fk))))
    ((_ v (pat e0 e ...) cs ...)
     (let ((fk (lambda () (pmatch1 v cs ...))))
       (ppat v pat (let () e0 e ...) (fk))))))

(define-syntax ppat
  (syntax-rules (_ quote unquote)
    ((_ v _ kt kf) kt)
    ((_ v () kt kf) (if (null? v) kt kf))
    ((_ v (quote lit) kt kf)
     (if (equal? v (quote lit)) kt kf))
    ((_ v (unquote var) kt kf) (let ((var v)) kt))
    ((_ v (x . y) kt kf)
     (if (pair? v)
         (let ((vx (car v)) (vy (cdr v)))
           (ppat vx x (ppat vy y kt kf) kf))
         kf))
    ((_ v lit kt kf) (if (eq? v (quote lit)) kt kf))))
