. Actress accepts the action-semantic description of a source language, and from it generates a compiler. The generated compiler translates its source program to an action, performs sort inference on this action, (optionally) simplifies it by transformations, and finally translates it to object code. The sort inference phase provides valuable information for the subsequent transformation and code generation phases. In this paper we study the problem of sort inference on actions. 1 Introduction Actress is an action-semantics directed compiler generator [4]. It accepts a formal description of the syntax and action semantics [10, 16] of a particular programming language, called the source language, and automatically generates a compiler that translates the source language to C object code. The generated compiler first translates each source program to an action, called the program action. Then it sort-checks the program action. Finally, it transforms the program action, and translates it...

When writing semantic descriptions of programming languages, it is convenient to have tools for checking the descriptions. With frameworks that use inductively defined semantic functions to map programs to their denotations, we would like to check that the semantic functions result in denotations with certain properties. In this paper we present a type system for a modular style of the action semantic framework that, given signatures of all the semantic functions used in a semantic equation defining a semantic function, performs a soft type check on the action in the semantic equation. We introduce