NaN compatibility #248
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NaN compatibility #248
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wader
reviewed
Dec 19, 2024
| which breaks basic laws about total orders.) | ||
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| Like jq, jaq prints `nan` and `infinite` as `null` in JSON, | ||
| because JSON does not support encoding these values as numbers. |
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Was intentional to remove the part about null as JSON?
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Yes, because that section is about differences wrt jq, not about resemblances. In the same spirit, I have already removed other sections that once talked about a difference, but later became obsolete (in particular the section on recursive functions).
wader
approved these changes
Dec 19, 2024
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Thanks for having had a look at this, @wader! |
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| } else if left.is_nan() && right.is_nan() { | ||
| // there are more than 50 shades of NaN, and which of these | ||
| // you strike when you perform a calculation is not deterministic (!), | ||
| // therefore `total_cmp` may yield different results for the same calculation | ||
| // so we bite the bullet and handle this like in jq | ||
| Ordering::Less | ||
| } else { | ||
| f64::total_cmp(&left, &right) |
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This code still allows for -NaN and +NaN comparison nondeterminism when one of the inputs is non-NaN.
01mf02
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Dec 23, 2024
Thanks to @workingjubilee for spotting this. (<#248 (comment)>)
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This aligns jaq's and jq's handling of NaN (not a number), by enforcing
nan < nan.Before this change, it could happen that operations that yielded
nancould have introduced non-deterministic behaviour, see #243. With this PR, the non-deterministic floating-point behaviour is still there, but it should not be observable anymore.