Extreme explorations of TypeScript's type system
You can do some truly silly things with sufficiently ridiculous uses of typescript.  I built a typecheck-time spell checker[0] in it such that:  import { ValidWords } from "./spellcheck";
  
  // Typechecks cleanly:
  const result: ValidWords = "valid";
  
  // Throws a type error
  const result: ValidWords = "valid";


[0] https://github.com/kkuchta/TSpell