What does it mean if there is a lambda with a nullable receiver?

this

can == null in the body of the lambda?

fun foo(block: String?.() -> Unit)

vs

fun foo(block: String.() -> Unit)

I noticed that with the second I cannot call

.block()

on a

String?

but the lambda body (for block param where foo is used) stays the same.

I see you found your answer already, but yes,

this

can be null in Kotlin, https://pl.kotl.in/H169XXRp7 for very simple example