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Re: [PATCH] Fast R6RS div/mod; improved extensibility of numerics


From: Andy Wingo
Subject: Re: [PATCH] Fast R6RS div/mod; improved extensibility of numerics
Date: Mon, 31 Jan 2011 20:26:22 +0100
User-agent: Gnus/5.13 (Gnus v5.13) Emacs/23.2 (gnu/linux)

On Mon 31 Jan 2011 18:35, Mark H Weaver <address@hidden> writes:

> Andy Wingo <address@hidden> writes:
>>> The last patch might be slightly controversial.  Although it does not
>>> make `integer-expt' a generic function, nonetheless it can now
>>> exponentiate _any_ scheme object that can be multiplied using `*'.
>>
>> To me this is fine, in principle; but I wonder about causing `(expt #t
>> 0)' to produce 1.  It seems that in any case the range of the output
>> should be continuous -- i.e. if (expt <my-matrix> 1) produces a matrix,
>> and (expt <my-matrix> n) for n > 1 makes a matrix, then (expt
>> <my-matrix> 0) should also produce a matrix.  Or no?
>
> When using generic arithmetic operators, there's no way to return
> objects of the correct type in all corner cases like this.

Well... OK!  I'm feeling reckless, so I'm applying and pushing your
patch.  Here goes nothing!

Andy
-- 
http://wingolog.org/



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