;; This modules provides runtime support for the syntax transformer
;; code in rpn-tx.ss 

(module rpn-runtime mzscheme
  
  (provide (all-defined))

  ;; A normal primitive is applied to the data stack. A delayed one
  ;; needs to be forced first.
  
  (define (apply/force promise stack)
    (apply (force promise) stack))


  ;; Transform a primitive into a 'state' word, one that operates on
  ;; stack' if the original stack == (state . stack')

  (define (state-lift word)
    (and word
         (lambda (state . stack)
           (cons state (apply word stack)))))

  ;; The same is done for immediates, which are treated separatedly
  ;; from functions in the compiler, and can use a pre-bound procedure.

  (define (state-immediate thing stack)
    (cons (car stack)
          (cons thing (cdr stack))))


  
  
  )