Union on Associations (Kernel Kill)

Question

Bug introduced in 10.1 and fixed in 10.2.0

Perhaps Union on Associations is not being encouraged since Join is preferred given Key-Value shadowing.

Join[<|a -> 1|>, <|a -> 1|>]

<|a -> 1|>

Join[<|a -> 1|>, <|a -> 2|>]

<|a -> 2|>

... although doing so by a complete kernel kill seems a tad drastic?

Union[<|a -> 1|>, <|a -> 2|>]

(* i.e. don't evaluate if you don't want to lose current definitions *)

At first pass, shouldn't Union do the same thing as Join on Associations? — Ronald Monson, Jul 14 '15 at 00:45
This is a bug and has been fixed in version 10.2 which should be available very soon. — ilian, Jul 14 '15 at 00:50
@ilian Do you know when the bug first appeared? I would like to mark it in this post if possible. — Mr.Wizard, Jul 14 '15 at 00:51
@Mr.Wizard 10.1.0 @Ronald Monson It will return unevaluated since it is not specified how the associations should be merged, but one could use Merge instead. — ilian, Jul 14 '15 at 01:22

score 5 · Accepted Answer · edited Apr 13 '17 at 12:55

5

Posting ilian's comment as an answer.

This bug has been fixed in version 10.2.0.

$Version
Union[<|a -> 1|>, <|a -> 2|>]
(* "10.2.0 for Linux x86 (64-bit) (July 6, 2015)" *)
(* <|a -> 1|> \[Union] <|a -> 2|> *)

edited Apr 13 '17 at 12:55

Community

answered Jul 23 '15 at 10:28

jkuczm

1 Answers1