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Last active December 19, 2018 22:04
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scala contramap example
Raw
gistfile1.txt
F[A] Ordering[Int]
B => A listing => listing.id
F[B] Ordering[Listing]
val intOrderer: Ordering[Int]
val listingOrderer: Ordering[Listing] = intOrderer.contraMap(listing => listing.id)
See: http://igstan.ro/posts/2013-10-31-contravariant-functors-an-intuition.html
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