[merijnv]

ugh, I see HN bollocksed my list and I can't edit it to fix it, so repeated for readability:

- Type theory (Benjamin Pierce's "Types and Programming Languages" is the de facto introduction to this. It covers everything from untyped lambda calculus to things way more complex than standard Haskell, including example implementations of type checker, etc.)

- Computer assisted proofs/formal verification of programs (the Software Foundations book series, co-authored by Pierce are a good (and free!) intro: https://softwarefoundations.cis.upenn.edu/)

- The Spineless Tagless G-machine (if you are a more low level/C minded person, this talks about how we compile a lazy functiona language like Haskell to an Intel CPU: http://citeseer.ist.psu.edu/viewdoc/summary?doi=10.1.1.53.37...)

- The Typeclassopedia (which talks about how various CT inspired classes relate to each other and their laws: https://wiki.haskell.org/Typeclassopedia)