Strange behavior with delayed objects

[user8472]

I am currently working through SICP using Guile. I have found some strange
behavior when doing the exercises in chapter 3.5. I am running Guile 1.4
installed via Fink on Mac OS X 10.6, all latest patches installed. The
problem also exists in Guile 1.8.6.

This code works fine (and computes e):
  (define y (integral (delay dy) 1 0.001))
  (define dy (stream-map (lambda (x) x) y))
  (stream-ref y 1000)

The following code *should* be identical:
  (define (solve f y0 dt)
    (define y (integral (delay dy) y0 dt))
    (define dy (stream-map f y))
    y)
  (solve (lambda (x) x) 1 0.001)

But it yields the error message:
standard input:7:14: While evaluating arguments to stream-map in expression
(stream-map f y):
standard input:7:14: Unbound variable: y
ABORT: (unbound-variable)

So when embedded in a procedure definition, the (define y ...) does not
work, whereas outside the procedure it works fine.

What am I doing wrong here? I can post the auxiliary code (i.e., the
definitions of integral, stream-map etc.) if necessary, too.
-- 
View this message in context: 
http://old.nabble.com/Strange-behavior-with-delayed-objects-tp28443452p28443452.html
Sent from the Gnu - Guile - User mailing list archive at Nabble.com.