[Ecls-list] Extension to infinity and NaN?

[Goffioul Michael]

> On Wed, 2005-07-20 at 13:32 +0200, Goffioul Michael wrote:
> > Do you think that extending ECL to support inifinity and 
> NaN as special
> > numbers is possible (without too much effort)? I know this 
> is not part
> > of ANSI, but it can be very convenient.
> 
> The effort is precisely on ensuring that it does not 
> contradict the ANSI
> semantics. Do you know how this is handled, say for instance, 
> in CMUCL?

It uses special constants defined in the EXT package. See for example
http://common-lisp.net/project/cmucl/doc/cmu-user/extensions.html#toc7.
But as you say, the problem is to not contradict ANSI. Thinking about
it, does ANSI state that (/1 0) MUST signal an error? Looking at
HyperSpec, it uses MIGHT. From CMUCL doc, it seems that this depends
on some trapping flag.

it's a pity that such constants are not part of ANSI...

Michael.