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Re: Making 'eq' == 'eql' in bignum branch

From: Ken Raeburn
Subject: Re: Making 'eq' == 'eql' in bignum branch
Date: Tue, 28 Aug 2018 03:34:35 -0400

On Aug 27, 2018, at 22:25, Pip Cet <address@hidden> wrote:
> On Tue, Aug 28, 2018 at 1:50 AM Lars Ingebrigtsen <address@hidden> wrote:
>> But anyway, as Richard implies, it's a read syntax that's strangely
>> difficult to remember.  Would it make sense to have a variable like
>> `positive-infinity' (etc) or `math-positive-infinity'?  Or perhaps we'll
>> all start remembering it after seeing it sprinkled throughout the source
>> code after a while.
> How about making (min) = 1.0e+INF and (max) = -1.0e+INF? That would be
> easier to type, and it's mathematically correct. We could even
> optimize it in the bytecode compiler.

That’s great if you’re applying max or min to a possibly-empty collection of 
values. But if you’ve got a loop where you’re tracking a minimum/maximum value 
along with doing other stuff (possibly including computing the values you’re 
looking for the minimum of), this may not help much.

If “1.0e+INF” is hard to remember, how about defining symbols “+inifinity” and 
“-inifinity” (and if you want to get fancy with the Unicode, +∞ and -∞) with 
the appropriate numeric values? I kind of like the nil idea too.

There’s no reason we couldn’t do some or all of the above. Only question is, 
should “(min nil)” return nil or infinity?


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