We present a type-based flow analysis for simply typed lambda calculus with booleans, data-structures and recursion. The analysis is exact in the following sense: if the analysis predicts a redex, there exists a reduction sequence (using standard reduction plus context propagation rules) such that this redex will be reduced. The precision is accomplished using intersection typing. It follows that the analysis is non-elementary recursive – more surprisingly, the analysis is decidable. We argue that the specification of such an analysis provides a good starting point for developing new flow analyses and an important benchmark against which other flow analyses can be compared. Furthermore, we believe that the techniques employed for stating and proving exactness are of independent interest: they provide methods for reasoning about the precision of program analyses. A preliminary version of this paper has previously been published (Mossin 1997b). The present paper extends, elaborates and corrects this previously published abstract.

AnnoDomini is a source-to-source conversion tool for making COBOL programs Year 2000 compliant. It is technically and conceptually built upon type-theoretic techniques and methods: type-based specification, program analysis by type inference and type-directed transformation. These are combined into an integrated software reengineering tool and method for finding and fixing Year 2000 problems. AnnoDomini's primary goals have been flexibility (support for multiple year representations), completeness (identifying all potential Year 2000 problems), correctness (correct fixes for Year 2000 problems) and a high degree of safe automation in all phases (declarative specification of conversions, no second-guessing or dangerous heuristics).In this paper we present the type-theoretic foundations of AnnoDomini: type system, type inference, unification theory, semantic soundness, and correctness of conversion. We also describe how these foundations have been applied and extended to a common COBOL mainframe dialect, and how AnnoDomini is packaged with graphical user interface and syntax-sensitive editor into a commercially available software tool.

Applications of partial evaluation have so far mainly focused on generation of compilers from interpreters for programming languages. We partially evaluate a simple general LR(k) parsing algorithm. To obtain good results, we rewrite the algorithm using a number of binding-time improvements. The final LR(1) parser has been specialized using Similix, a partial evaluator for a higher order subset of Scheme [3]. The obtained specialized parsers are efficient and compact.