Union on Associations (Kernel Kill)

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 0:45
• Reproducible crash confirmed in 10.1.0 under Windows. – Mr.Wizard Jul 14 '15 at 0:50
• This is a bug and has been fixed in version 10.2 which should be available very soon. – ilian Jul 14 '15 at 0:50
• @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 0:51
• @ilian Ok, (error message or same output as Join) – Ronald Monson Jul 14 '15 at 0:51

1 Answer

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|> *)