;; implecations

(define-syntax implecations
  (syntax-rules (=>)
    ((_ (pred => body ...) ...)
     (begin
       (when pred
         body ...)
       ...))))

(let ((x 0)(y 0)(hoge "hello")(false #f))
  (implecations ((zero? x) => (display x)(newline))
                ((number? y) => (format #t "~a is number." y))
                (false =>  (print hoge))
                (#t =>  (print "world !"))))
;; 0
;; 0 is number.world !
;; #<undef>