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.sort() doesn't work correctly #605
Description
[2,11].sort()
# expected (python):
[2,11]
# result of JavaScript's [2,11].sort() (used by Transcrypt.__runtime__.js in __sort__)
[11,2]
This is a classic JavaScript 'gotcha' since it will sort the elements as if they were strings, even if the elements are all numbers! It will sort correctly for most small numbers making it a tricky bug to catch as well.
Activity
JdeH commentedon Jan 10, 2019
Indeed that's a problem, and not one that can be solved completely due to the lack of type info in JS.
One pragmatic solution would be to regard anything that could be a number as indeed being a number. This would sort the list as [2, 11], but it would also produce ['2', '11'] as sorting result from a list of strings. Since the case of sorting list containing only numbers or only non-numerical strings will probably will be far more frequent than the case of sorting a list with both numbers and numerical strings, I think the latter would be acceptable.
Type annotations could avoid ambiguity here, but I'd like to keep their use optional, since to many Python programmers they are still a bit alien... One way to do it is to consider a list that starts with a number or numerical string as containing only numbers. Still there would be some overhead in detecting that (and, but it would be better than having [11, 2] as result.
Whatever solution is choosen, the limitations of it should receive attention in the documentation.
faerot commentedon Jan 17, 2019
maybe resolving it just like you did with other overlapping pythoin/JS methods - adding py_sort and adding pragma which will enable pythonic sort with key function etc wherever necessary?
supersational commentedon Jan 30, 2019
Hi thanks for looking into this, definitely agree with your goal of avoiding type annotations.
Python's .sort() will throw an error unless all list elements are type "string" or a mix of number and boolean. So if the first element is a string type sort all as a string, if first element is a number (or boolean), sort all as numbers (and throw an error if any aren't of the required type).
erelsgl commentedon Nov 2, 2019
I have the same issue. Is there a workaround?
supersational commentedon Nov 5, 2019
You can fix by forcing a numerical sort
JennaSys commentedon Jul 7, 2024
Sorting with strings vs numbers to match CPython has been somewhat fixed in the dev_3.9.3 branch to be released in v3.9.3
A limitation for now is that it will still allow comparisons between incompatible values like
intandstrwhere CPython would throw an error. Adding type validation to sorting to match CPython would add bloat to the runtime and likely be imperfect anyway. This can be revisited in the future if necessary.JennaSys commentedon Jul 17, 2024
Merged to master on PR #876