private/binding.ss
(module binding mzscheme

  (require "require.ss")
  (require-lists)

  (provide
   sexp->binding
   binding->sexp
   binding-lift
   (struct binding (key value)))

  ;; A (Binding Key Value) is (make-binding Key Value)
  (define-struct binding (key value))

  ;; binding->sexp : (Binding Key Value) -> (list Key Value)
  ;; Builds a list from a binding.
  (define (binding->sexp binding)
    (list (binding-key binding) (binding-value binding)))

  ;; sexp->binding : (list Key Value) -> (Binding Key Value)
  ;; Builds a binding from a list.
  (define (sexp->binding sexp)
    (make-binding (first sexp) (second sexp)))

  ;; binding-lift : (Key ... -> T) -> ((Binding Key Any) ... -> T)
  ;; Consumes a function operating on keys.
  ;; Produces a function operating on bindings.
  (define (binding-lift key-fn)
    (lambda bindings
      (apply key-fn (map binding-key bindings))))

  )