Supertypes RE: Extensible Enumerated types

["Robert C. Leif, Ph.D." <rleif@rleif.com>]

From: Bob Leif
To: My fellow Ada users

This is suggestion includes the addition of a new keyword to Ada. I realize
that some would consider this rank heresy.

Since Ada has Subtypes to specify a subset of a type, it would be reasonable
to create a symmetrical operation to create a superset of a type.

-- from Package Prefix_Recs
type Prefix_Type is (None, Mr, Ms, Miss, Mrs, Dr, Prof, Rev,
    Other);

--From Package Prefix_Recs.Army
Supertype Army_Prefix_Type is (Prefix_Type, Private, Corporal, Sergeant,
Lieutenant, Captain, Major, Colonel, General);

Prefix_Type'range would also be a possibility.

Army_Prefix_Type would inherit all of the operations of Prefix_Type.

I believe that super is lexicography a better choice than supra. I must add
that supertypes are appropriate for a super language.