On 4/13/13 1:18 PM, Jerzy Karczmarczuk wrote:

This is not a Haskell problem. For Ints, ALL representations are valid numbers, a NaN is a specific float object, unless I'm mistaken, so the introduction of such an abnormal number would require some serious modifications of the representation.

Also, the necessity of NaN for floats comes from the fact that floats include values for Infinity and -Infinity, which leads to various equations which cannot be resolved sensibly. This is different than mere undefinedness. Undefined values are underspecified, but that can often be resolved by choosing some arbitrary specification (often chosen via arguing from limits or combinatorial convenience). Whereas the problematic values due to infinities are overspecified, so no matter which answer you pick it's guaranteed to be the wrong answer half the time. Part of this whole problem comes from the fact that floats *do* decide to give a meaning to 1/0 (namely Infinity). That's the gateway drug,... -- Live well, ~wren