Clojure's threading macro in scheme

threading.scm

(define-syntax ->
  (syntax-rules ()
    ([_ value]
     value)
    ([_ value snd rest ...]
     (cond
      [(list? 'snd)
       (let ([f (primitive-eval (car 'snd))]
             [args (cons value (cdr 'snd))])
         (-> (apply f args) rest ...))]
      [(procedure? snd)
       (-> (snd value) rest ...)]))))

(define-syntax -»
  (syntax-rules ()
    ([_ value]
     value)
    ([_ value snd rest ...]
     (cond
      [(list? 'snd)
       (let ([f (primitive-eval (car 'snd))]
             [args (append (cdr 'snd) (list value))])
         (-» (apply f args) rest ...))]
      [(procedure? snd)
       (-» (snd value) rest ...)]))))


;;=> 2
(-> 1 1+ (+ 1 1) (/ 2))

;;=> 0.5
(-» 1 1+ (+ 1 1) (/ 2))