HKU PL Group

We are a group of programming language researchers who study topics about functional language design, type theory, compilers and program analysis.
The University of Hong Kong

Higher-rank Polymophism on a Dependent Type System


The higher-rank polymorphism is a language feature that allows polymorphic types to appear in arbitrary position of a type, not just top-level. Joshua Dunfield and @Jimmy Zhao have investigated the local type inference of higher-rank polymorphism on a non-dependent type system that resembles system-F, where they made use of subtyping as a tool to formalize a “more-general” relation between polymorphic and monomophic types.

In my very first seminar in the group, I will be introducing my current research progress of generalizing such subtyping relation to a dependent type system. We are using the “Unified Subtyping” developed by @Linus Yang to untie the potential mutual dependency between typing and subtyping for a dependently-typed language, which was a issue that introduced major complexity in other previous works with subtyping and dependent types.

Hopefully we will develop a reasonable metatheory for the system :D.