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> NaN's are already an option type, although implemented in hardware The compromise with this is that it makes it impossible to represent a non-optional float,

> NaN's are already an option type, although implemented in hardware The compromise with this is that it makes it impossible to represent a non-optional float, which leads to the same issues as null pointers in c++/java/etc. The impacts of NaN are almost certainly not as bad (in aggregate) as `null`, but it'd still be nice if more languages had ways to guarantee that certain numbers aren't NaN (e.g. with a richer set of number types).

jcranmer 4y ago
> The impacts of NaN are almost certainly not as bad (in aggregate) as `null`, but it'd still be nice if more languages had ways to guarantee that certain numbers aren't NaN (e.g. with a richer set of number types). The problem with that is that to guarantee arithmetic does not result in a NaN, you need to guarantee that 0 and infinity are not valid values, and those values can still arise from underflow/overflow of regular computation. Basically, there's no subset of floating-point numbers that forms a closed set under +, -, *, or / that doesn't include NaN. So you can define FiniteF32 (e.g.), but you can't really do anything with it without the result becoming a full-on float.