Kotlin 1.3

Is there any public roadmap for Kotlin 1.3?

I’m particularly interested in collection literals.


Since I had the same interested in the past (and today), I suggest to put a “roadmap” link on the homepage. The roadmap itself could link KEEP issues.

Nothing in https://github.com/Kotlin/KEEP for collection literals. Does that mean they’re not expected any time soon?

Collection literals are not such a great idea. For an explanation:

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That just means they couldn’t come up with a good solution. Ideally there would be a combination of compiler and library support, as was done for coroutines.

There have been a few suggestions of how to do this already, including some from JetBrains engineers. The general idea is that { ... }, with an inferred or declared type, will trigger the compiler to find a method with a specific name and signature which can create that type.

Why do you need Collection Literals? There’s a standerd functions like mapOf(), listOf() & setOf() and much more to get things done.

{1:a, 2:b, 3:c, 4:d, 5:e, 6:f, 7:g}
mapOf(1 to a, 2 to b, 3 to c, 4 to d, 5 to e, 6 to f, 7 to g)

is much cleaner, particularly in DSLs. Groovy Gradle scripts containing maps are a good example, they become very ugly when translated into Kotlin script.


From my point of view an “association” operator (like : in your example) would be sufficient. I consider the library approach to be more clean from a platform perspective.

mapOf(1:a, 2:b, 3:c, 4:d, 5:e, 6:f, 7:g)

I think the biggest pain point are DSLs. Having collection literals would open up very nice possibilities in DSLs. Gradle scripts are a good benchmark.


KEEP for Collection Literals: https://github.com/Kotlin/KEEP/issues/113

What’s the current status of 1.3? I see a new branch 1.3-M1 on Kotlin’s repository. Looks like they are planning to introduce unsigned types. Is there any tentative roadmap?


Funny. Working with collections in Java is traditionally a huge PITA.

A proposal for collection literals which is an alternative to the one from @BenLeggiero, at https://github.com/Kotlin/KEEP/pull/229, with discussion at https://github.com/Kotlin/KEEP/issues/230. I hatched this idea ages ago, before I read your proposal, Ben, but I got some useful inspiration from it, so thanks for that. I’m approaching it in a somewhat different way.

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