commander-s/scheme/eval-environment.scm

(define *evaluation-environment*)
(define *evaluation-environment-name*)
(define *user-environment* #f)

(define (load-evaluation-environment package)
  (let ((structure (reify-structure package)))
    (load-structure structure)
    (rt-structure->environment structure)))

(define (evaluation-environment-name)
  (if (eq? *evaluation-environment*
           *user-environment*)
      (string->symbol "") ; aehm...
      *evaluation-environment-name*))

(define (set-evaluation-package! package-name)
  (set! *evaluation-environment*
        (load-evaluation-environment package-name))
  (set! *evaluation-environment-name* package-name))

(define (init-evaluation-environment! user-env)
  (set-evaluation-package! user-env)
  (set! *user-environment* (evaluation-environment)))

(define (evaluation-environment)
  *evaluation-environment*)

(define (read-sexp-from-string string)
  (let ((string-port (open-input-string string)))
    (read string-port)))

(define (eval-string str)
  (eval (read-sexp-from-string str)
        (evaluation-environment)))

(define (eval-s-expr s-expr)
  (eval s-expr (evaluation-environment)))