Is there any particular reason that ``` class ReactMap MutableMap lt Long MutableList lt EmoteData gt gt by mutableMapOf lt Long MutableList lt EmoteData gt gt withDefault mutableListOf lt EmoteData gt ``` compiles fine and ``` class ReactMap MutableMap lt Long MutableList lt EmoteData gt gt by mutableMapOf ``` compiles fine but ``` class ReactMap MutableMap lt Long MutableList lt EmoteData gt gt by mutableMapOf withDefault mutableListOf ``` doesn t Is it a bug in the compiler or is it intentional

Is there any particular reason that ``` class ReactMap Mutab kotlinlang #announcements

01/10/2019, 4:15 AM

Is there any particular reason that

class ReactMap : MutableMap<Long, MutableList<EmoteData>> by (mutableMapOf<Long, MutableList<EmoteData>>()
    .withDefault { mutableListOf<EmoteData>() })

compiles fine, and

class ReactMap : MutableMap<Long, MutableList<EmoteData>> by mutableMapOf()

compiles fine, but

class ReactMap : MutableMap<Long, MutableList<EmoteData>> by (mutableMapOf().withDefault { mutableListOf() })

doesn't? Is it a bug in the compiler, or is it intentional?

01/10/2019, 12:46 PM

It's because the

mutableMapOf()

invocation can't infer type arguments in the last example. It might work if you enable the improved type inference, but I'm not sure.

01/10/2019, 5:31 PM

How do I enable that?

01/10/2019, 5:42 PM

I'm not sure, look for the blog post on 1.3 I guess

It should be a compiler argument

tasks.withType<KotlinCompile> {
        kotlinOptions {
            jvmTarget = "1.8"
            freeCompilerArgs = listOf(
                "-XXLanguage:+InlineClasses",
                "-XXLanguage:+NewTypeInference",
                "-Xuse-experimental=kotlin.Experimental"
            )
        }
    }

^ Using kotlin gradle DSL

-XXLanguage:+NewTypeInference