Bug introduced in 10.1 or earlier and fixed in 10.3

According to the documentation, in order to make sure that a value in an association is not evaluated at initialization, one can use a RuleDelayed. This works fine:

assoc = <| "a" -> x, "b" :> (x = 1;) |>;

{ assoc["a"], assoc["b"]; assoc["a"] }

Now, I want to have a key that clears the association if I extract its value. Like this:

assoc = <| "clear" :> Clear[assoc] |>;

However, any Mathematica expression that is executed after assigning assoc clears assoc (in Mathematica 10.1). What is going on?


It turns out this is a bug caused by the Suggestions Bar as pointed out by the user ilian. Turning off the Suggestions Bar in Edit->Preferences->Interface fixed the issue.

  • 1
    $\begingroup$ I'm not quite following: Can you give one example of "executing any command" that does this? $\endgroup$ Jul 17, 2015 at 17:50
  • 6
    $\begingroup$ @Praan Try turning off the Suggestions bar. $\endgroup$
    – ilian
    Jul 17, 2015 at 17:57
  • $\begingroup$ @Arnoud Buzing Literally anything. Any Mathematica expression that is executed after assigning assoc clears assoc. $\endgroup$
    – Praan
    Jul 17, 2015 at 18:00
  • $\begingroup$ @ilian It worked! Thanks! $\endgroup$
    – Praan
    Jul 17, 2015 at 18:18

1 Answer 1


To turn my comment into an answer, this seems to be an evaluation leak coming from the Predictive Interface. I've let the appropriate developers know and they will look into it.

A workaround for now would be to turn off the Suggestions bar.


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