SetBased Analysis for Full Scheme and Its Use in SoftTyping.pdfVIP

SetBased Analysis for Full Scheme and Its Use in SoftTyping Cormac Flanagan Matthias Fel leisen Rice COMP TR Octob er Department of Computer Science Rice University PO Box Houston TX c Copyright by Cormac Flanagan and Matthias Felleisen SetBased Analysis for Full Scheme and Its Use in SoftTyping Cormac Flanagan Matthias Felleisen Department of Computer Science Rice University Houston TX Abstract SetBased Analysis is an ecient and accurate program analysis for higherorder lan guages It exploits an intuitive notion of approximation that treats program variables as sets of values We present a new derivation of setbased analysis based on a reduc tion semantics that substantially simplies previous formulations Most imp ortantly the derivation easily extends from a functional core language to include imp erative features such as assignments and rstclass continuations and supp orts the rst cor rectness pro of of setbased analysis for these imp erative features The pap er includes an implementation of the derived analysis for a Schemelike language and describ es a softtyping algorithm that eliminates typ echecks based on the information pro duced by the analysis  Supp orted in part by NSF