cond-list

cond-list pasted by alaricsp on Tue Apr 8 12:25:55 2014

(define-syntax cond-list
  (syntax-rules ()
    ((cond-list) (list))
    ((cond-list (c e) . rest)
     (if c
         (cons e (cond-list . rest))
         (cond-list . rest)))))

#;2> (cond-list)
()
#;3> (cond-list (#t 1) (#t 2))
(1 2)
#;4> (cond-list (#t 1) (#f 2))
(1)
#;5> (cond-list (#f 1) (#f 2))
()
#;6> (cond-list (#f 1) (#t 2))
(2)

cond-list generating less code pasted by DerGuteMoritz on Tue Apr 8 16:21:21 2014

(define-syntax cond-list
  (syntax-rules ()
    ((cond-list) (list))
    ((cond-list (c e) ...)
     (let ((tail (cond-list rest ...)))
       (if c
           (cons e tail)
           tail)))))

fixed a typo in DerGetMoritz's version added by alaricsp on Tue Apr 8 16:24:39 2014

(define-syntax cond-list
  (syntax-rules ()
    ((cond-list) (list))
    ((cond-list (c e) rest ...)
     (let ((tail (cond-list rest ...)))
       (if c
           (cons e tail)
           tail)))))