It's this contramap :: (a -> b) -> f b -> f a http://hackage.haskell.org/package... | Hacker News

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		boothead on Jan 13, 2016 \| parent \| context \| favorite \| on: How we used Category Theory to solve a problem in ... It's this `contramap :: (a -> b) -> f b -> f a http://hackage.haskell.org/package/contravariant-1.3.3/docs/Data-Functor-Contravariant.html#v:contramap`

pka on Jan 13, 2016 [–]

I thought "Extension" in this example is a Monoid. So maybe foldContramap? :)

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