(define-syntax-rule (begin0 exp exps ...)
  (call-with-values
      (lambda () exp)
    (lambda vals
      exps ...
      (apply values vals))))

(define-syntax-rule (let-env ((var val) ...) exp exp* ...)
  (let ((old-env (environ)))
    (for-each setenv (list var ...) (list val ....))
    (begin0
      (begin exp exp* ...)
      (environ old-env))))