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From: | Paul Eggert |
Subject: | Re: integer overflow handling for most-negative-fixnum |
Date: | Sat, 21 Jul 2018 10:46:05 -0700 |
User-agent: | Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 |
Andy Moreton wrote:
Bignums are not relevant to this discussion.
I'm afraid they are. Whatever solution we come up with in this problem, should be compatible with bignums. Our solution should not assume that integers are of fixed width.
Non base10 representations of emacs fixnums are not treated consistently, and prevent round trip handling of the full range of valid fixnum values.
As Helmut mentioned, read and print work just fine. The problem is that if you use some formats, you don't get a round trip. Of course this problem is endemic to formats; e.g., (read (format "%g" X)) does not yield X for all floating-point values X, due to rounding. Still, it would be helpful if the usual kind of formatting hex integers were round-trip more often. I'll propose something along these lines in my next email.
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