Clojure

• Type: Defect
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: Release 1.4
• Fix Version/s: None
• Component/s: None
• Labels:

  None

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.

1. 

   clj-1036-hasheq-for-biginteger-patch-v2.txt

   13/Nov/12 9:44 PM

   4 kB

   Andy Fingerhut

• Assignee:

  Unassigned

  Reporter:

  Paul Stadig

• Created:

  02/Aug/12 8:41 AM

  Updated:

  12/Apr/13 8:48 AM