Data.Void

newtype Void

An uninhabited data type. In other words, one can never create a runtime value of type Void because no such value exists.

Void is useful to eliminate the possibility of a value being created. For example, a value of type Either Void Boolean can never have a Left value created in PureScript.

This should not be confused with the keyword void that commonly appears in C-family languages, such as Java:

public class Foo {
  void doSomething() { System.out.println("hello world!"); }
}

In PureScript, one often uses Unit to achieve similar effects as the void of C-family languages above.

absurd :: forall a. Void -> a

Eliminator for the Void type. Useful for stating that some code branch is impossible because you've "acquired" a value of type Void (which you can't).

rightOnly :: forall t . Either Void t -> t
rightOnly (Left v) = absurd v
rightOnly (Right t) = t