#lang typed/racket

(require)

(provide Symbol VariableMapping
         eval-with eval1-with)

(module+ test
  (require typed/rackunit))

;;; ===================
;;; HashTable injection
;;; ===================

(define-type Variable Symbol)
(define-type (VariableMapping A) (Immutable-HashTable Variable A))

(: eval-with (-> (VariableMapping Any) Any AnyValues))
(define (eval-with ht expr)
  (parameterize ([current-namespace (make-base-namespace)])
    (for ([(x val) (in-hash ht)]) (namespace-set-variable-value! x val))
    (eval expr)))

(: eval1-with (-> (VariableMapping Any) Any Any))
(define (eval1-with ht expr)
  (call-with-values (λ () (eval-with ht expr))
                    (λ args (car args))))

(module+ test
  (test-case "eval-with"
    (check-equal? (eval1-with (hash 'a 1 'b 2) '(+ a b 1))
                  4)
    (define ht : (VariableMapping Integer) (hash 'a 1 'b 2))
    (define expr : Any '(+ a b 1))
    (check-equal? (eval1-with ht expr)
                  4)))