[Scm-discuss] nested define question

[Tom Kwong]

Hi,

Can someone please explain why the following nested define structure does not work?
Thanks in advanced.

SCM version 5e7, Copyright (C) 1990-2006 Free Software Foundation.

> (define (abc)
  (define (a) 1)
  (define b (a))
  (print b))
(abc)
#<unspecified>
> 
;ERROR: unbound variable:  a
; in _expression_: (a)
; in scope:
;   (b a . address@hidden)
;   ()

Compare with the letrec version:

> (define (abc)
  (letrec ((a (lambda () 1))
       (b (a)))
    (print b)))
(abc)
#<unspecified>
> 1 
1