Re: [Emacs-diffs] master 37940b3: min and max now return one of their arguments

[Paul Eggert]

On 03/08/2017 07:54 AM, Eli Zaretskii wrote:
> Don't programmers
> assume in general that comparisons between values some of which are
> floats are always done after converting_all_  values to the
> floating-point representation?

No, and that hasn't been true for Emacs Lisp for quite some time. In 
Emacs 25, (<= 10000000000000001 10000000000000000 1e16) returns the 
mathematically-correct answer nil on a 64-bit GNU/Linux host even though 
it would return t if all values were first converted to float.

More generally, although people expect statically typed languages to 
convert alternatives to float (e.g., C programmers expect (1.5 > 2 ? 1.5 
: 2) to return 2.0 not 2), dynamically typed languages are different: 
Lisp programmers expect (if (> 1.5 2) 1.5 2) to return 2 not 2.0.

Admittedly the situation with min and max is not quite as simple as with 
'if' (which clearly should not convert). Still, it's verrrry strange for 
(< A (min A B)) to return t, and having 'min' return the numerically 
correct answer avoids nonsensical behavior like that.


> I find the commentary in 'arithcompare' not detailed enough
I installed the attached, which I hope helps.

0001-src-data.c-arithcompare-Add-comments.patch
Description: Source code patch