@@ -0,0 +1,233 @@
+package org.hummingbirdlang.types.concrete;%0A%0Aimport org.hummingbirdlang.types.ConcreteType;%0A%0Apublic final class NullType extends ConcreteType %7B%0A  public static final NullType SINGLETON = new NullType();%0A%0A  private NullType() %7B%0A  %7D%0A%7D%0A

Add `NullType` to type-system