Closed Type Families with Overlapping Equations
- Richard A. Eisenberg ,
- Dimitrios Vytiniotis ,
- Simon Peyton Jones ,
- Stephanie Weirich
Proceedings of the 41st ACM SIGPLAN-SIGACT Symposium on Principles of Programming Languages |
Published by ACM
Open, type-level functions are a recent innovation in Haskell that move Haskell towards the expressiveness of dependent types, while retaining the look and feel of a practical programming language. This paper shows how to increase expressiveness still further, by adding closed type functions whose equations may overlap, and may have non-linear patterns over an open type universe. Although practically useful and simple to implement, these features go beyond conventional dependent type theory in some respects, and have a subtle metatheory.
Here is an extended version with proofs.