Plotkin's call-by-value λ-calculus as a modal calculus

Abstract

In the authors' previous analysis of the calling paradigms call-by-name and call-by-value through Girard's and Gödel's embeddings into the S4 modal logic, an asymmetry remains: the two paradigms are unified by the call-by-box paradigm of the modal target, but only for call-by-name can one say that the paradigm exists, up to isomorphism, inside the modal target. In this paper, we show that, by pushing further the modal analysis, a symmetric situation is revealed, in that ordinary and Plotkin's λ-calculi are shown to truly co-exist inside a simple modal calculus.