Nothing

stdlib / kotlin / Nothing

kotlin/core/builtins/native/kotlin/Nothing.kt

public class Nothing private() {}

Nothing has no instances. You can use Nothing to represent “a value that never exists”. for example. if a function has the return type of Nothing. it means that it never returns.

How to use

When you represent a null is should I use Nothing.

>>> fun crash(x:Nothing) {}
>>> crash("foo")
error: type mismatch: inferred type is String but Nothing was expected

>>> fun crash(x:Nothing?) {}
>>> crash(null)