I'm having trouble using minByOrNull within buildMap, getting odd type mismatch errors about TypeVar...

# getting-started

[David Glasser]

I'm having trouble using minByOrNull within buildMap, getting odd type mismatch errors about TypeVariables. Am I missing something? https://pl.kotl.in/GnuWqAS_Z

[David Glasser]

(I'm trying to make a Map out of another Map by first filtering it based on one condition, and then removing the smallest element based on a second condition. I figure buildMap is a nice way to not have to have an explicit MutableMap in the middle. But minByOrNull doesn't work on the this of the buildMap closure for some reason...)

[David Glasser]

OK I guess it's a type inference thing; specifying <String, F> myself on buildMap (or its return value) works

[asdf asdf]

You could also simplify output into something like this for more readability / avoiding type inference oddities:

Untitled.kt

[David Glasser]

@asdf asdf thanks, but in the real version I'm doing a remove on the output of the minByOrNull 🙂

[Stephan Schröder]

your code also works if you add type annotations to buildMap

val output = buildMap<String, F> {

looks like you reached the limits of type inference

[ilya.gorbunov]

@David Glasser I've simplified your example and filed an issue https://youtrack.jetbrains.com/issue/KT-57834/Cannot-infer-type-of-keys-and-values-of-buildMap-builder

[David Glasser]

thanks!