1.9.0

• Renamed _Unit to _SameObject — unit was a bad name for this
• Significantly improved subtype checking
  • Deferred types are now unwrapped during subtype checking
  • Infinite loops are detected
  • Improved subtype logic — for example constraints are subtypes of their parameters, e.g. _Constraint(Array, size: 10) is a subtype of Array
  • Introduced _Kind type as a way to create higher order types. For example _Kind(Integer) is the type of the type of an integer.
• Introduced _TaggedUnion which is like a _Union but with tags for each enumerant. This makes it possible to do schema based serialisation of unions.
• Various bug fixes and improvements
• Introduced experimental monadic result objects: Literal::Result, Literal::Success, Literal::Failure
• Added support for mapping some types to other types. For example, you can now map a union of types to a union of kinds.
• Added support for descriptions on properties