I expected that a Map is a Map, and the

in

operator would be consistently interpreted as

containsKey(..)

. The fact that it does not cost me over an hour of debugging, and I think is a surprising result for users. I would expect to be able to switch a collection between

HashMap

,

ConcurrentHashMap

, ... any

Map

and have the code behave consistently.

brett.wooldridge: I think its neither of both. The

in

operator is mapped to

contains()

in kotlin. So the problem with ConcurrentHashMap is, that it defines its own legacy

contains()

which calls

containsValue()

. There is not really a way to override the behaviour of

ConcurrentHashMap.contains()

outside of the class itself

Please report this in kotl.in/issue. It at least deserves an inspection warning in IDE. Maybe there is something that can be done in the language for this special case, but I wouldn't expect this.

ok

👍

By the way, I love the bejesus out of Kotlin. Been using it for ~8 months and I look forward to opening the IDE everyday.

You may want to send it directly to #random instead of in thread so more people see it. JB devs like to see happy users 🙂

Hard to resist the temptation to go back and rewrite something that is already working every time I learn something new. 🙂