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

From: Andy Moreton
Subject: Re: Making 'eq' == 'eql' in bignum branch
Date: Mon, 20 Aug 2018 17:58:00 +0100
User-agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1.50 (windows-nt)

On Mon 20 Aug 2018, Paul Eggert wrote:

> Andy Moreton wrote:
>> The current codebase assumes that lisp bignum objects only exist for
>> values outside fixnum range. Without fixnump how can tests check that
>> values within fixnum range actually have a fixnum representation
> Tests cannot possibly check that, because 'fixnump' itself might simply return
> t for any integer in fixnum range, even if the integer is internally
> represented as a bignum.

Only true if the tests can make no assumptions about the implementation.
As the tests and the codebase are developed together that need not be
the case.

> Besides, the current codebase is not actually assuming that Lisp bignum
> objects exist only for values outside fixnum range (the current codebase is
> not assuming that bignums exist at all, for that matter).

The C code most certainly does assume this. The lisp code does not care
about representation (other than tripping over various bignum bugs that
need fixing).


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