#lang racket/base

(require "main.rkt"
         racket/contract)

(provide define/contract/return
         (all-from-out racket/contract)
         (all-from-out "main.rkt")
         )

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; define/return/contract
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(define-syntax define/contract/return
  (syntax-rules ()
    ((_ (name . formals) return (c ... last-pred) b1 ...)
     (define/contract (name . formals)
       (c ... last-pred)
       (call/cc
        (λ (ret)
          (define/contract
            (make-ret x)
            (-> any/c last-pred)
            x)
          (define (return x)
            (ret (make-ret x)))

          b1
          ...
          )
        )))
    ((_ name last-pred value)
     (define/contract name
       last-pred
       (call/cc
        (λ (ret)
          (define/contract
            (make-ret x)
            (-> any/c last-pred)
            x)
          (define (return x)
            (ret (make-ret x)))
          value))))
    )
  )

#|
(define-syntax def-returner
  (syntax-rules ()
    ((_ pred name)
     (define/contract (name x)
       (-> any/c pred)
       (return-value x))
     )
    )
  )

(define-syntax call-returner
  (syntax-rules ()
    ((_ x name)
     (name x))))

(define-syntax define/contract/return
  (syntax-rules ()
    ((_ (name . formals) (c ... last-pred) b1 ...)
     (define/contract (name . formals)
       (c ... last-pred)
       
       (let ((ret (λ (x)
                    (def-returner last-pred name)
                    (call-returner x name))))
         (with-handlers ([exn:return? ret])
           b1
           ...)))
     )
    ((_ name last-pred value)
     (define/contract name
       last-pred
       (let ((ret (λ (x)
                    (def-returner last-pred name)
                    (call-returner x name))))
         (with-handlers ([exn:return? ret])
           value)))
     )
    )
  )

|#