Package com.vladris.maki

Class Never

java.lang.Object

com.vladris.maki.Never

public final class Never
extends java.lang.Object

Represents an uninhabitable type.

Never is impossible to instantiate, thus it can be use to denote absence of a value. The following example shows two use-cases of Never: explicitly showing a method does not return and as a generic type argument to remove the type option.

 class Sample {
     // This function never returns
     static Never Fail(String message) throws Exception {
         throw new Exception(message);
     }

	   // This function also never returns
     static Never LoopForever() {
         while (true) {
         }
     }
     
     // Assume a generic library method which expects an Either<T, U>
     static <T, U> void NeedsGenericEither(Either<T, U> either) {
         // ...
     }
     
     static void Example() {
         // We can remove a type from Either by providing Never
         Either<Integer, Never> either = new Either<Integer, Never>(42);
 
         NeedsGenericEither(either);
     }
 }
 

Method Summary

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait