# Immutable map - put / add
**URL:** https://discuss.kotlinlang.org/t/immutable-map-put-add/354
**Category:** Uncategorized
**Created:** [January 8, 2015, 6:58pm UTC](https://discuss.kotlinlang.org/t/immutable-map-put-add/354 "2015-01-08T18:58:22Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@kocka](https://discuss.kotlinlang.org/u/kocka)
#### Post date: [January 8, 2015, 6:58pm UTC](https://discuss.kotlinlang.org/t/immutable-map-put-add/354/1 "2015-01-08T18:58:22Z")
Hi all,
What is the shortest/best way of creating an immutable map from another immutable map plus a new element possibly overriding an element?
Is there a reason why the + - operators are not supported?
Regards,
Laszlo
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### Author:  [@abreslav](https://discuss.kotlinlang.org/u/abreslav)
#### Post date: [January 11, 2015, 11:38am UTC](https://discuss.kotlinlang.org/t/immutable-map-put-add/354/2 "2015-01-11T11:38:20Z")
Side note: those are not **immutable** maps, but **read-only** maps. They may be mutated elswhere, but the reference we are holding does not permit mutation.
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### Author:  [@kocka](https://discuss.kotlinlang.org/u/kocka)
#### Post date: [January 11, 2015, 2:34pm UTC](https://discuss.kotlinlang.org/t/immutable-map-put-add/354/3 "2015-01-11T14:34:29Z")
Ah yes indeed, read-only is a better expression.
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### Author:  [@kocka](https://discuss.kotlinlang.org/u/kocka)
#### Post date: [January 11, 2015, 2:37pm UTC](https://discuss.kotlinlang.org/t/immutable-map-put-add/354/4 "2015-01-11T14:37:10Z")
Meanwhile, I have registered a feature request for this: [https://youtrack.jetbrains.com/issue/KT-6594](https://youtrack.jetbrains.com/issue/KT-6594)