Higher Rank Types

How?

• Lecture
• Code snippets

What?

• What are higher rank types — semi formal definition (Rank 1 Types, Rank 2 Types)
• Possible use cases
• How it’s not so easily done in Haskell
• How it’s easily done in TypeScript
• Why you can’t do it in Haskell (strong type inference)
• Why you can in TypeScript (week type inference)

Why?

• More like a fun fact
• Most of you probably haven’t heard about it, but the same time most of you is using them on a daily basis
• Haskell vs TS

Agenda

1. Intro

2. Why am I talking about Higher Rank Types?

3. What is it?

4. Higher ranks

5. Example

6. Haskell limitations

Resources

• https://wiki.haskell.org/Rank-N_types
• https://en.wikibooks.org/wiki/Haskell/Polymorphism
• https://softwareengineering.stackexchange.com/questions/277048/is-higher-rank-parametric-polymorphism-useful
• https://www.sciencedirect.com/science/article/pii/S0168007298000475