Impredicative Higher-RankTypes

Stc
Date: Dec 16

Time: 11:45

Room: CGN room C004

Speaker: Daan Leijen

Title: Impredicative Higher-Rank Types

Abstract

In this talk I will give an overview of the ML-F type system: a system with higher-rank polymorphic types. Higher-rank type systems offer more abstraction than standard Hindley-Milner types. In the talk, I give examples of first-class modules and generic iterators.

ML-F is the first (and only) type system that supports impredicative type inference. In practice this means that the system is compositional where data structures can hold polymorphic values and generic functions can be applied to polymorphic arguments. Note that this is not the case for the (predicative) higher-rank type extension of Haskell.

The material on the mlF type system is in general difficult to read, and I will try to make this more accessible by showing demos in the Morrow interpreter and by highlighting the most important technical achievements.