Use custom strings ordering when sorting

We would like to use custom ordering function when sorting matched documents. Right now ordering uses simple Go string comparison, but we would prefer to use ordering by using Collator (or more generally by custom Less function).

How would you suggest to implement such feature?

I see at least two possibilities:

• change SortOrder type into a struct with Less function.
• keep SortOrder as-is (slice), but change SortOrder.Compare function to take explicit Less function. This would require propagation of Less function from SearchRequest