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GET of a HUNK
- To: JONL at MIT-MC
- Subject: GET of a HUNK
- From: Kent M. Pitman <KMP at MIT-MC>
- Date: Sun, 15 Feb 81 16:39:00 GMT
- Cc: BUG-LISP at MIT-MC
- Original-date: 15 February 1981 11:39-EST
Date: 13 February 1981 20:03-EST
From: Jon L White <JONL>
Date: 12 February 1981 23:39-EST
From: Richard L. Bryan <RLB at MIT-MC>
How much cpu time have YOU wasted waiting for your program to run,
when it turns out it was looping infinitely, doing GET off some extend?
...I ALWAYS SAID THAT HUNKS SHOULD PASS THE ATOM TEST!! SOOOO, I've just
edited in the source the code for GET and GETL to distinguish between LIST
non-atoms and HUNK non-atoms, and return () for the latter.
It REALLY bugs me that these things aren't discussed in advance. I don't
like this change and I would like it retracted. It is bad for two reasons:
(1) It can break code. I haven't had time to analyze my packages to see
if it does, but I don't use USRHUNK at all -- I like just bare hunks
and I have used them as CDR-able objects and as objects with plists on
a number of occasions. I don't know if I currently have code that cares
and haven't had time to look. Even if it doesn't break any code, it
radically changes the way in which hunks must be viewed as a tool for
implementation -- i think NOT for the better.
(2) It is not uniform with the treatment of non-user-hunks and the value of
HUNKP elsewhere in Lisp. Please do not make changes to the language
which are not coherent with what little overall design philosophy there
is still persisting in Maclisp after all the other changes that have
been forced upon it to get NIL going.
The correct fix would have been to make only USRHUNKs have the behavior
you described. I would have no objection to that, as it is both safe and