Types and type inference in a visual programming language

The uses of types and type inference in visual languages are explored. First, we discuss how the goals of a type system must differ from visual languages from those of a type system for textual languages. We then present a type system developed under these goals for the visual language Forms/3. Within the context of this system, issues of particular importance in visual languages are examined, including maintaining the user´s conceptual model, the avoidance of language restrictions solely to support a type system, and how the visual process of programming can provide additional information to the type system