;;
;; The macro "and-." expands to a pair unless its second argument is #f
;; or (if a third argument is given) the third argument is #f
;;
(define-syntax and-.
  (syntax-rules ()
    ((and-. x y) (and y (cons 'x  y)))
    ((and-. x y z) (and z (cons 'x  y)))))
;;
;; The macro "filter-true" filters all elements equal to #f from a list.
;;
(define-syntax filter-true
  (syntax-rules ()
    ((filter-true lst) (filter (lambda(x) x) lst))))
;;
;; The macro "boolean" turns its argument into either #t or #f
;;
(define-syntax boolean
  (syntax-rules ()
    ((boolean x)(and x #t))))
;;
;; The macro "pipify" just provides some syntactic sugar around pipejoin.
;;
(define-syntax pipify
  (syntax-rules ()
    ((pipify x)
     (if (pair? x) (pipejoin x) x))))