env.scm

(define obj (make-top-level-environment))
(environment-define obj 'foo (lambda (x) (+ x bar)))
(environment-define obj 'bar 10)
((environment-lookup obj 'foo) 1)
; Unbound variable: bar
;; This works:
(define obj (extend-top-level-environment #f))
(eval '(define (foo x) (+ x bar)) obj)
(environment-define obj 'bar 10)
((environment-lookup obj 'foo) 1)
; 11