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Re: Error objects in general



Paul Schlie wrote:
Overall the question is: if NaN's (aka <indeterminate>/<void> values) are
to be embraced, should their observable effect be more generally defined
throughout the entire language specification? (As otherwise the ambiguities
they represent may either be obscured by subsequent evaluations, or result
in potentially undesirable non-easily foreseen halting errors?)

It seems reasonable to specify:

(a) The rules for arithmetic on NaNs.

(b) The behaviour of eqv? on NaNs.

(c) The read and write syntax of NaNs, if these exist.

(d) That calling inexact->exact on a NaN signals an error.

Provided one maintains (d), the effects of NaNs are limited.

Regards,

Alan
--
Dr Alan Watson
Centro de Radioastronomía y Astrofísica
Universidad Astronómico Nacional de México