Set-Based Analysis for Full Scheme and Its Use in Soft-Typing

Set Based Analysis is an e cient and accurate program analysis for higher order lan guages It exploits an intuitive notion of approximation that treats program variables as sets of values We present a new derivation of set based analysis based on a reduc tion semantics that substantially simpli es previous formulations Most importantly the derivation easily extends from a functional core language to include imperative features such as assignments and rst class continuations and supports the rst cor rectness proof of set based analysis for these imperative features The paper includes an implementation of the derived analysis for a Scheme like language and describes a soft typing algorithm that eliminates type checks based on the information produced by the analysis Supported in part by NSF grant CCR and a sabbatical at Carnegie Mellon University