1. A language designed for its simple denotational semantics.
"The Denotational Semantics of Programming Languages",
R. Tennent, CACM 19(8):437-453 (Aug 1976).
2. QUantifiers and SubTypes. Language with a sophisticated
type system. Just as types classify values, "kinds" classify
types and type operators. Explicit universal and existential
quantification over types, type operators, and subtypes.
Subtyping is defined inductively on all type constructions,
including higher-order functions and abstract types.
User-definable higher-order type operators.
45, DEC SRC 1989.
Implemented in Modula-3.
been available for
MS-DOS for some time. Version 3.5 for
(1995-04-02)