I have a `mutableListOf<Pair?>` that I want ...

# getting-started

[kv]

I have a mutableListOf<Pair?> that I want to check the contents of. I try something like this on Kotlin 1.5.21:

fun foo(value: List<Pair?>): Boolean {
        return list.contains(value)
    }

I get the following error:

Type inference failed. The value of the type parameter T should be mentioned in input types (argument types, receiver type or expected type). Try to specify it explicitly.

I can remove the error by modifying it to return list.contains<Any?>(value) but it feels like a weird work around. Anyone got insight as to the best way to approach this?

[ephemient]

a (Mutable)List<Pair?> should never contain a List<Pair?> element. do you mean containsAll?

[Casey Brooks]

The snippet infers that list is List<List<Pair?>. .containsAll would check that all elements of value are also elements of list, where the two are both List<Pair?>

[kv]

interesting kotlin 1.4.0 didn't flag it as a compile-time error

[kv]

so android studio lets me build when 1.4.0 (with a lint warning), but when I bump to 1.5.21, it flags it as a compile-time error