The Sather Specification - Types and Classes Go to the first , previous , next , last section, table of contents . Abstract types represent sets of concrete types.
External types specify interfaces to other languages.
The type graph for a program is a directed acyclic graph that is constructed from the program's source text. Its nodes are types and its edges represent the subtype relationship. If there is a path in this graph from a type t1 to a type t2, we say that t2 is a subtype of t1 and that t1 is a supertype of t2. Every Sather variable has a declared type. The signature of a routine consists of its name, the types of its arguments, if any, and its return type, if any.