. Dynamic binding, which has always been associated with Lisp, is still semantically obscure to many. Although largely replaced by lexical scoping, not only does dynamic binding remain an interesting and expressive programming technique in specialised circumstances, but also it is a key notion in semantics. This paper presents a syntactic theory that enables the programmer to perform equational reasoning on programs using dynamic binding. The theory is proved to be sound and complete with respect to derivations allowed on programs in "dynamic-environment passing style". From this theory, we derive a sequential evaluation function in a context-rewriting system. Then, we exhibit the power and usefulness of dynamic binding in two different ways. First, we prove that dynamic binding adds expressiveness to a purely functional language. Second, we show that dynamic binding is an essential notion in semantics that can be used to define the semantics of exceptions. Afterwards, we further refin...

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This paper proposes some (unimplemented) ideas for the compilation of Scheme-like languages where functions may be specialized with respect to some of the continuations with which they are invoked. This allows for some optimizations, for instance, when a frame to be pushed and the frame on top of the continuation can be combined into a single and simplified frame. Among possible improvements are: intermediate data structure elimination and removal of useless calculations. Functions can therefore be compiled with respect to their near future and reorganize it when appropriate. The compilation technique is based on a program transformation named Abstract Continuation Passing Style that makes continuation (i.e. stack) frames explicit. Shape of continuations is approximated to determine which frames would gain by being combined together then partial evaluation is used to determine the behavior of combined frames. Our main results cover local deforestation-like effect as well as iterative c...

This paper presents a compilation technique for Scheme-like languages where functions may look at their continuation before pushing frames onto it. This allows for some optimizations when the frame to be pushed and the frame on top of the continuation can be combined into a single and simplified frame. Among possible simplifications are: intermediate data structure elimination and removal of redundant calculations. Functions can therefore be compiled with respect to their near future and reorganize it when appropriate. The compilation technique is based on an improved CPS-like transformation that makes continuation (i.e. stack) frames explicit. Shape of continuations is approximated to determine which frames would gain by being combined together then partial evaluation is used to determine the behavior of combined frames. Our main results cover local deforestation-like effect as well as iterative compilation of associatively wrapped recursions. This paper presents a compilat...

This note was written at the occasion of the retirement of Jean-Francois Perrot at the Universite Pierre et Marie Curie (Paris VI). In an attempt to emulate his academic spirit, we revisit an example proposed by Patrick Greussay in his doctoral thesis: how to verify in sublinear time whether a Calder mobile is well balanced. Rather than divining one solution or another, we derive a spectrum of solutions, starting from the original specification of the problem. We also prove their correctness.

machines, expressed with the help of Felleisen’s evaluation contexts, for a toy functional language. Then we add a simple control operator and extend the abstract machines accordingly. We give some examples of their use. Then, restricting our attention to the sole core (typed) λ-calculus fragment augmented with the control operator, we give a logical status to the machinery. Evaluation contexts are typed “on the left”, as they are directed towards their hole, or their input, in contrast to terms, whose type is that of their output. A machine state consists of a term and a context, and corresponds logically to a cut between a formula on the left (context) and a formula on the right (term). Evaluation, viewed logically, is cut-elimination: this is the essence of the so-called Curry-Howard isomorphism. Control operators correspond to classical reasoning principles, as was first observed by Griffin. 1 A simple call-by-value evaluator Consider the following simple functional programming language, whose data types are (nonnegative) integers and lists.