[plt-scheme] Stepper problems

From: Jens Axel Søgaard (jensaxel at soegaard.net)
Date: Wed Sep 18 13:10:05 EDT 2002

Hi all,

One of my students wrote this contains-waterpistol? program:

(define (indeholder-vandpistol? l)
    [(empty? l) false]
       [(symbol=? (first l) 'vandpistol) true]
       [else (indeholder-vandpistol? (rest l))])]))

(indeholder-vandpistol? (cons 'bold (cons 'vandpistol empty)))

When executed it returns true.

I told him, as I told the others, to try it in the stepper, but for
some reason the stepper never starts. The garbage collector
kicks in and eventually I have to kill DrScheme.

The other programs ran fine (I think they used (cons? l) instead
of else in the first conditional), so I'm wondering whether
it is a bug in the stepper, or just something simple, I overlooked.

The behaviour is consistent across win98/winXP/Linux, version 201.

Jens Axel Søgaard

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