Compiling Rust is NP-hard | Hacker News
https://news.ycombinator.com/item?id=27769718
Refinement type - Wikipedia
https://en.wikipedia.org/wiki/Refinement_type
r/ProgrammingLanguages - Singleton, Fiber and Equivalence
https://www.reddit.com/r/ProgrammingLanguages/comments/abcnmf/singleton_fiber_and_equivalence/
singleton_fiber_equivalence
https://k-bx.github.io/articles/singleton_fiber_equivalence.html