A Definite and Unfoldable, Partially Deterministic Language

Abstract

We define a simple non-deterministic functional language that has definite variables and where function application is unfoldable. This language demonstrates that Sondergaard and Sestoft's claim, that in a non-deterministic language we cannot obtain both definiteness and unfoldability, assumes a fairly general notion of non-determinism. Our language relies on using a restricted notion of non-determinism called partial determinism