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.
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