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Re: Stream-filter and space leaks

This page is part of the web mail archives of SRFI 40 from before July 7th, 2015. The new archives for SRFI 40 contain all messages, not just those from before July 7th, 2015.

>>>>> "RK" == Richard Kelsey <kelsey@xxxxxxx> writes:

RK>    From: Phil Bewig <pbewig@xxxxxxxxxx>
RK>    Date: Thu, 20 Feb 2003 15:08:05 +0100

RK>    Stream-filter and
RK>    the various stream-drop functions leak space if they are not implemented
RK>    properly, something that is hard to do.  In fact, in a private e-mail
RK>    yesterday someone pointed out another space leak involving stream-filter
RK>    (they were also kind enough to show how to fix it).

RK> Comparing the new version of STREAM-FILTER with the one in the proposed SRFI,
RK> it appears that this latest space leak could be fixed by including your own
RK> versions of DELAY and FORCE in the sample implementation, using one where forcing
RK> a stream caused it to stop retaining the generating thunk.  You could merge this
RK> delay into the STREAM record:

The code you posted seems to be essentially the definition of
DELAY/FORCE from Scheme 48.  However, Phil's old code does leak in
Scheme 48 and doesn't leak with the proposed fix.  This is just a
note---I intend to check next week why this is so.

Cheers =8-} Mike
Friede, Völkerverständigung und überhaupt blabla