A Relational Solver for Constraint-based Type Inference

Abstract

We present a miniKanren-based type inferencer for an educational programming language with first-class functions, S-expressions, and pattern-matching. The language itself is untyped which adds a certain specificity to the problem and requires the employment of techniques conventionally used in implicit/gradual typing settings. The presence of polymorphic and recursive types poses a certain challenge when implementing the inferencer in miniKanren and requires a number of tricks, optimizations, and extensions to be used; we report on those as well.