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Date: Mon, 24 Oct 2005 04:08:32 +0200 From: Marcin 'Qrczak' Kowalczyk <qrczak@xxxxxxxxxx> Taylor Campbell <campbell@xxxxxxxxxx> writes: > CL conditions *are* comparable to NaN. No, because they are passed out of band. They are not returned as results of arithmetic operations nor accepted by arithmetic. So they won't be printed along with other numeric results, and it makes no sense to read them back in place of numbers. Did you read what I wrote? CL conditions do *not* exist only if they are immediately signalled out-of-band; they can exist in-band in any situation you want. Likewise, NaN is a condition of numerical operations, which, for the sake of floating-point efficiency, it is convenient in some contexts to allow along with other numerical results. But NaN conditions can be signalled like error conditions can be; this is typically what is done with exact arithmetic, such as in Scheme48: (/ 0 0) => Error: rational division by zero 0