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

From: Pip Cet
Subject: Re: Making 'eq' == 'eql' in bignum branch
Date: Mon, 20 Aug 2018 07:19:39 +0000

On Mon, Aug 20, 2018 at 7:06 AM Paul Eggert <address@hidden> wrote:
> Hold on, let's not spend that valuable tag so casually! Perhaps bignums or
> floats are a better use for a tag than 64-bit ints.

Considering it's only those 64-bit ints that don't fit into 61 (or 62,
or 30, or 29) bits already, I'm no longer convinced this is a good
idea at all. At the very least, it would make our interpreter code
harder to read.

> One other thing: we can pry another tag free. Now that we have bignums we no
> longer need to give fixnums two tags.

I think too many places might still assume that most-positive-fixnum
is precisely either one of its current values (OTOH, I'm running with
most-positive-fixnum = 0x7fffffff and things appear to work).

I think references to most-positive-fixnum (and implicit ones, like
using Frandom without an argument) should be eliminated. Fixnum range
is now an implementation detail.

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