Abusing the continuation monad

(Recall that monads are not a good topic for your first blog post.)

I intend to bootstrap a blog by writing about 2 of my old papers, Monad Transformers for Backtracking Search and The Selection Monad as a CPS Transformation. (Wall Street will be spared for the time being.)

I’m going to write about this little bit of Haskell code:

import Control.Monad.Cont
sat n = runCont $ sequence $ replicate n $ cont $ \k -> k $ k True

It’s a SAT solver: you give it a boolean function, and the number of variables to search, and it decides whether that function will ever return true for any values of those variables.

How does this work? Haven’t the foggiest. If anyone can explain what it does at runtime, there’s probably a research paper in it for you. If you can also predict how long it takes, that’s a big deal.

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