Type Inference & Unification - Isaac Elliot - BFPG 2019-03

The podcast provides a concise analysis of type inference, beginning with a refresher on notation, BNF style syntax descriptions, and natural deduction rules. It extends simply-typed lambda calculus with an unannotated lambda term, addressing the challenge of determining the type to attach to a variable when typing the lambda's body. The introduction of metavariables as placeholders for types during type checking is a key component. The discussion covers how to infer types for applications and IF rules, including the use of constraints to ensure type compatibility. The podcast further explores the unification algorithm, substitutions, and the occurs check, addressing performance considerations and the handling of polymorphism through type variables and schemes.