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Re: Stream-filter and space leaks



>>>>> "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