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sperber@xxxxxxxxxxxxxxxxxxxxxxxxxxx (Michael Sperber [Mr. Preprocessor]) writes: > >>>>> "Matze" == Matthias Neubauer <neubauer@xxxxxxxxxxxxxxxxxxxxxxxxxx> writes: > > Matze> Richard Kelsey <kelsey@xxxxxxx> writes: > > >> Our different experiences may be based on differences between the 0.57 and > >> the Scheme 48 version underlying Scsh 0.6.3. I don't know which version > >> that is. > > Matze> Well, that's what I already feared. To me, this means either that my > Matze> scsh is somehow "buggy" or that we still don't have a portable, > Matze> non-leaking implementation of STREAM-FILTER. > > There's no way to do that in general. However, if you take the code > Phil posted last and lambda-lift the internal definitions out, you'll > get something that works pretty much everywhere (certainly in Scheme > 48 and scsh), I conjecture. Yes, this does the trick. After lambda-lifting STREAM-FILTER, (stream-car (stream-filter (lambda (x) (zero? x)) (stream-from 1))) also loops in my scsh. The real problem is see is the following: as soon as I apply some kind of abstraction over STREAM-FILTER---which is something every Schemer wants to do of course---, hell breaks loose again. E.g., if I type (define (filter-zero stream) (stream-filter (lambda (x) (zero? x)) stream)) (stream-car (filter-zero (stream-from 1))) in scsh, I will again see a space leak. Considering all the major Scheme implementations, how common is it to use a flat closure representation for procedures? -Matthias -- Matthias Neubauer | Universität Freiburg, Institut für Informatik | tel +49 761 203 8060 Georges-Köhler-Allee 79, 79110 Freiburg i. Br., Germany | fax +49 761 203 8052