Welcome to the CHICKEN Scheme pasting service

(define a 1)
(print a)
(eval `(set! a 2))
(print a) ; 2

(module
 c
 *
 (import chicken scheme)
 (define b 1)
 (print b)
 (eval `(set! b 2))
 (print b) ; 1
)

(import c)
(print b)

(define a 1)
(print a)
(eval `(set! a 2))
(print a) ; 2

(module
 c
 *
 (import chicken scheme)
 (define b 1)
 (print b)
 (define (foo)
  (eval `(set! b 2) (module-environment 'c))) ; Error: unbound variable: set!

 (foo)
 (print b) ; 1
)

(import c)
(print b)