Ask HN: Favourite resources for learning programming type theory?

by stephantul on 3/19/2025, 7:46:14 PM with 8 comments
Hello HN,

Recently, I've been massively enjoying diving into type checkers and how to effectively use them (mostly in Python).

I lack foundational knowledge about the topic (I never studied CS), however, so I am looking for introductory textbooks/blogs/resources on the topic.

More specifically: I see terms being thrown around like "Algebraic sum type", "covariant", "contravariant", and I would like to understand more about what they mean and imply in a practical sense.

Thanks!

  • by kingkongjaffa on 3/24/2025, 8:34:17 AM

    This blog is chock full of these ideas, start here:

    https://jrsinclair.com/articles/2019/algebraic-data-types-wh...

  • by nbaksalyar on 3/20/2025, 12:02:00 AM

    > introductory textbooks/blogs/resources on the topic

    Books on TypeScript, OCaml, Rust or Haskell are usually great resources for that.

    There's also "Thinking with Types" which addresses this topic in a lot of depth:

    https://thinkingwithtypes.com/

  • by i_don_t_know on 3/22/2025, 7:37:36 AM

    Types and Programming Languages by Benjamin Pierce, sometimes also referred to as TAPL.

  • by randomNumber7 on 3/19/2025, 9:19:46 PM

    I enjoyed some papers of Luca cardelli (when I remember the name correctly). There is also one overview/introduction about dependent type systems he wrote.

    This is all very theoretically heavy though.