Random generators for dependent types

Paper i proceeding, 2004

We show how to write surjective random generators for several different classes of inductively defined types in dependent type theory. We discuss both non-indexed (simple) types and indexed families of types. In particular we show how to use the relationship between indexed inductive definitions and logic programs: the indexed inductive definition of a type family corresponds to a logic program, and generating an object of a type in the family corresponds to solving a query for the logic program. As an example, we show how to write a surjective random generator for theorems in propositional logic by randomising the Prolog search algorithm.