Thanks @marstran, but if

Unit

is the

void

equivalent, why is it assignable in kotlin but not in java?

This is a misunderstanding.

Unit

isn't the

void

equivalent. The problem is

void

in Java is playing two roles and doesn't distinguish between them. Java can't distinguish between a function that returns, but doesn't return a useful value (

Unit

in Kotlin

()

in Rust, etc.) and a function that doesn't return at all (usually called a diverging function) (

Nothing

in Kotlin,

!

in Rust, etc.)