Details
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Type:
Defect
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Status:
Open
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Priority:
Major
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Resolution: Unresolved
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Affects Version/s: Release 1.4
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Fix Version/s: None
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Component/s: None
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Labels:None
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Patch:Code and Test
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Approval:Not Approved
Description
The doc string for hash states that it defines a hash code function that is consistent with =, but for java.math.BigInteger hash is not consistent with =.
user=> (apply = [(Long. -1) -1N (biginteger -1)]) true user=> (map hash [(Long. -1) -1N (biginteger -1)]) (0 0 -1) user=>
It is possible to have a PHM with two key/value pairs where the keys are equal, and the hash codes are different:
user=> (assoc clojure.lang.PersistentHashMap/EMPTY (biginteger -1) :oops! -1N :one)
{-1N :one, -1 :oops!}
The expected behavior is the same as PersistentArrayMap, which does not have this issue, because it does not hash its keys:
user=> (assoc clojure.lang.PersistentArrayMap/EMPTY (biginteger -1) :oops! -1N :one)
{-1 :one}
This same misbehavior also occurs for Doubles and Floats:
thalia.core=> (apply = [(Float. 1e9) (Double. 1e9)]) true thalia.core=> (map hash [(Float. 1e9) (Double. 1e9)]) (1315859240 1104006501)
That leads to the same difference in array-map and hash-map behavior as above for BigInteger and BigInt.
