ezyang’s blog

the arc of software bends towards understanding

Duality for Haskellers

This post is the spiritual predecessor to Flipping Burgers in coBurger King. What does it mean for something to be dual? A category theorist would say, “It’s the same thing, but with all the arrows flipped around.” This answer seems frustratingly vague, but actually it’s quite precise. The only thing missing is knowing what arrows […]

  • October 19, 2012