motlin

public int factorial(int n)
{
    if (n < 1)
    {
        error("n less than 1. <" + n + ">");
    }
    return n == 1 ? 1 : n * factorial(n - 1);
}

motlin

public MyObject myMethod(MyParameter myParameter)
{
    return undefined();
}

// vs.

public MyObject myMethod(MyParameter myParameter)
{
    undefined();

motlin

public static <T> T undefined()
{
  throw new RuntimeException();
}

motlin

Map<Key, Value> map = ...;
Key key = ...;
Value value = map.get(key);

motlin

public interface Option<T>
{
    T get();
}

public class Some<T> implements Option<T>
{
    private final T value;

    public Some(T value)

motlin

val employee = map.get(employeeId)
if (employee == null) return;
val workAddress = employee.workAddress
if (workAddress == null) return;
println(workAddress.state.name)

// vs.

map.get(employeeId).flatMap(_.workAddress).map(_.state.name).foreach(println)

motlin

def undefined: Nothing = throw new RuntimeException
def undefined: Nothing = undefined
def undefined: Nothing = new Object().asInstanceOf[Nothing]

motlin

val i: Int = undefined
def undefined: Nothing // works
def undefined: Null // doesn't work since a primitive may not be null on the JVM

motlin

undefined :: a
error :: [Char] -> a

motlin

public enum None implements Option<Nothing>
{
    INSTANCE;

    public Nothing get()
    {
        throw new UnsupportedOperationException("None.get()");
    }
}