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Re: Pre-RFC: `unknown` versus `undef`

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From:
Darren Duncan
Date:
December 19, 2021 19:20
Subject:
Re: Pre-RFC: `unknown` versus `undef`
Message ID:
d6c83b42-e67f-c0d8-4c87-e80865669882@darrenduncan.net
On 2021-12-19 4:07 a.m., Oodler 577 via perl5-porters wrote:
> The closest concept I can think that I might be familiar with is Fortran's
> NaN, which is part of the IEEE arithmetic standards. It is composed of a
> special values that can be detected in hardware or software.

This again, the NaN concept of Fortran or IEEE floating point numbers, is 
another reason I actually advocate for a concept like I expressed with Excuse, 
where an explicit reason for a missing regular value is encoded in the 
not-regular-value result.  An Excuse duals for the concepts of unthrown 
exception as well as the concept of a NaN, of which there are several kinds, 
such as divide by zero, underflow, etc. -- Darren Duncan
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