(define srfi-126-dto
  (let ()

    (define (prep-dto-arg proc)
      (lambda (dto . args)
        (apply proc args)))
    
    (define (t126-hashtable-pure?* dto table)
      #f)

    (define (t126-hashtable-ref* dto table key fail success)
      (define-values (value found?) (t126-hashtable-lookup table key))
      (if found?
          (success value)
          (fail)))

    (define (t126-hashtable-ref/default* dto table key default)
      (t126-hashtable-ref table key default))

    (define (t126-hashtable-set* dto table . obj)
      (let loop ((obj obj))
         (if (null? obj)
             #t
             (begin
               (t126-hashtable-set! table (car obj) (cadr obj))
               (loop (cddr obj))))))

    (define (t126-hashtable-delete-all* dto table keys)
      (for-each
          (lambda (key)
            (t126-hashtable-delete! table key))
          keys))

    (define (t126-hashtable-intern* dto table key default)
      (t126-hashtable-intern! table key default))

    (define (t126-hashtable-update/default* dto table key updater default)
      (t126-hashtable-update! table key updater default))

    (define (t126-hashtable-pop* dto table)
      (if (t126-hashtable-empty? table)
          (error "popped empty dictionary")
          (t126-hashtable-pop! table)))

    (define (t126-hashtable-update-all* dto proc table)
      (t126-hashtable-update-all! table proc))

    (define (t126-hashtable-filter* dto proc table)
      (t126-hashtable-prune! table
                               (lambda (key value)
                                 (not (proc key value)))))

    (define (t126-hashtable-remove* dto proc table)
      (t126-hashtable-prune! table proc))

    (define (t126-hashtable-find-update* dto table key fail success)
      (define (handle-success value)
        (define (update new-key new-value)
          (unless (eq? new-key key)
              (t126-hashtable-delete! table key))
            (t126-hashtable-set! table new-key new-value))
        (define (remove)
          (t126-hashtable-delete! table key))
        (success key value update remove))
      (define (handle-fail)
        (define (ignore)
          table)
        (define (insert value)
          (t126-hashtable-set! table key value))
        (fail insert ignore))

      (define default (cons #f #f))
      (define found (t126-hashtable-ref table key default))
      (if (eq? default found)
          (handle-fail)
          (handle-success found)))

    (define (t126-hashtable-map->lset* dto proc table)
      (t126-hashtable-map->lset table proc))

    (define (t126-hashtable-keys* dto table)
      (vector->list (t126-hashtable-keys table)))

    (define (t126-hashtable-values* dto table)
      (vector->list (t126-hashtable-values table)))

    (define (t126-hashtable-entries* dto table)
      (call-with-values
          (lambda () (t126-hashtable-entries table))
        (lambda (keys vals)
          (values
           (vector->list keys)
           (vector->list vals)))))

    (define (t126-hashtable-comparator* dto table)
      #f)

    (make-dto
     dictionary?-id (prep-dto-arg t126-hashtable?)
     dict-pure?-id t126-hashtable-pure?*
     dict-empty?-id (prep-dto-arg t126-hashtable-empty?)
     dict-contains?-id (prep-dto-arg t126-hashtable-contains?)
     dict-ref-id t126-hashtable-ref*
     dict-ref/default-id t126-hashtable-ref/default*
     dict-set-id t126-hashtable-set*
     dict-delete-all-id t126-hashtable-delete-all*
     dict-intern-id t126-hashtable-intern*
     dict-update/default-id t126-hashtable-update/default*
     dict-pop-id t126-hashtable-pop*
     dict-map-id t126-hashtable-update-all*
     dict-filter-id t126-hashtable-filter*
     dict-remove-id t126-hashtable-remove*
     dict-find-update-id t126-hashtable-find-update*
     dict-size-id (prep-dto-arg t126-hashtable-size)
     dict-keys-id t126-hashtable-keys*
     dict-values-id t126-hashtable-values*
     dict-entries-id t126-hashtable-entries*
     dict-map->list-id t126-hashtable-map->lset*
     dict-comparator-id t126-hashtable-comparator*)))