A talk given at Philly Lambda on 5/27/2014 exploring subtyping variance and functor variance, including:

  • A review of subtyping invariance
  • Functor typeclass
  • Contravariant functor typeclass
  • Invariant functor typeclass
  • Profunctor typeclass
  • Correspondence between subtyping variance and functor variance

Slides and code available on GitHub.

Slides available on SpeakerDeck.