Using π—RED as a teaching tool for functional programming and program execution

Abstract

This paper describes an interactively controlled reduction system π-RED which may be employed to teach both basic concepts of functional programming and program execution at the undergraduate level, and advanced topics of computer science at the graduate level. π-RED supports the reduction languages KIR - a sugared versions of an applied λ-calculus with a full-fledged (type-free) β-reduction. Functions (λ-abstractions) are truly treated as first class objects: they may be applied to other functions or to themselves, and λ-abstractions may be computed as function values. Name clashes are resolved by an indexing scheme similar to de Bruijn indices. Programs may be executed in a stepwise mode and intermediate programs may be displayed in high-level notation. Special pattern matching constructs provide the means to directly specify in KIR complex term rewrite systems. In conjunction with the stepwise execution mode, this feature has been extensively used, in lab courses accompanying graduate courses on computer architecture, to rapidly prototype and study various programming and (abstract) machine models, compilation schemes, type checkers, etc.