Hi Isaac, Many thanks for the comments.
On Tue, Mar 2, 2021, at 14:34, Isaac Morland wrote: > One question I would have is whether empty ranges are all equal to each > other. If they are, you have an equality that isn’t really equality; if they > aren’t then you would have ranges that are unequal even though they have > exactly the same membership. Although I suppose this is already true for some > types where ends can be specified as open or closed but end up with the same > end element; many range types canonicalize to avoid this but I don’t think > they all do. I thought about this problem too. I don't think there is a perfect solution. Leaving things as they are is problematic too since it makes the range type useless for some use-cases. I've sent a patch in a separate thread with the least invasive idea I could come up with. > Returning to the RE result issue, I wonder how much it actually matters where > any empty matches are. Certainly the actual contents of the match don’t > matter; you don’t need to be able to index into the string to extract the > substring. The only scenario I can see where it could matter is if the RE is > using lookahead or look back to find occurrences before or after something > else. Hmm, I think it would be ugly to have corner-cases handled differently than the rest. > If we stipulate that the result array will be in order, then you still don’t > have the exact location of empty matches but you do at least have where they > are relative to non-empty matches. This part I didn't fully understand. Can you please provide some example on this? /Joel
