[Ecls-list] Extension to infinity and NaN?
der_julian at web.de
Wed Jul 20 07:51:21 UTC 2005
On Wed, 20 Jul 2005 16:15:20 +0200
"Goffioul Michael" <goffioul at imec.be> wrote:
> > 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
> 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.
Having (/ 1 0) signal no error violates the POLA for quite some users,
and is mathematically incorrect (infinity is no number). When does it
My two (euro) cents,
LISP has survived for 21 years because it is an approximate local
optimum in the space of programming languages. - John McCarthy (1980)
More information about the ecl-devel