Nested collection comparison
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Assessment
- Difficulty
- 5/5
- Estimated time
- Over a week
- Newbie friendliness
- 30/100
Research direction
Start at the db/value-compare entry point and reproduce the three comparison examples, especially vectors containing lists. Review how nested collection values are currently compared and the referenced Clojure APersistentVector comparison for context. Done would require an agreed comparison approach, coverage for the failing nested case, and tests for the existing successful cases.
Written by the indexing model from the issue text.
Description
(compare [1] [2]) ;; -1 is ok because vecotors are Comparable.
(compare '(1) '(2)) ;; BOOM throws an exception because lists are not Comparable, it's expected.
(compare ['(1)] ['(2)]) ;; BOOM it is also expected.
(db/value-compare [1] [2]) ;; -1
(db/value-compare '(1) '(2)) ;; -22.. it works because lists are compared by hash
(db/value-compare ['(1)] ['(2)]) ;; BOOM This case is too strange, I can compare vectors and lists but I can't compare vectors of lists.
I can wrap my vectors in a hash-map or a list and it works: (db/value-compare {:value ['(1)]} {:value ['(2)]}). But it's a hack.
Should we provide our own Compare protocol with hash support? In this case, we have to repeat a .compareTo method for all collections. It looks like .compareTo but calls our value-compare instead of Util/compare https://github.com/clojure/clojure/blob/c1ede7899d8d7dd4dcd6072d5c0f072b9b2be391/src/jvm/clojure/lang/APersistentVector.java#L439
This issue has a low priority.
- Dominant language
- Clojure
- Stars
- 5.8k
- Forks
- 318
- PR merge metrics
- No merged PRs in 30d
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