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[bpt/guile.git] / srfi / srfi-26.scm

(define-module (srfi srfi-26)
  :export (cut cute))

(cond-expand-provide (current-module) '(srfi-26))

(define-macro (cut slot . slots)
  (let loop ((slots	(cons slot slots))
	     (params	'())
	     (args	'()))
    (if (null? slots)
	`(lambda ,(reverse! params) ,(reverse! args))
      (let ((s	  (car slots))
	    (rest (cdr slots)))
	(case s
	  ((<>)
	   (let ((var (gensym)))
	     (loop rest (cons var params) (cons var args))))
	  ((<...>)
	   (if (pair? rest)
	       (error "<...> not on the end of cut expression"))
	   (let ((var (gensym)))
	     `(lambda ,(append! (reverse! params) var)
		(apply ,@(reverse! (cons var args))))))
	  (else
	   (loop rest params (cons s args))))))))

(define-macro (cute . slots)
  (let ((temp (map (lambda (s) (and (not (memq s '(<> <...>))) (gensym)))
		   slots)))
    `(let ,(delq! #f (map (lambda (t s) (and t (list t s))) temp slots))
       (cut ,@(map (lambda (t s) (or t s)) temp slots)))))