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missingfaktor/gist:1220623

Created September 15, 2011 22:07
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Contravariant functor
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gistfile1.scala
scala> case class Person(name: String, age: Int)
defined class Person
scala> implicitly[math.Ordering[Int]] contramap ((_: Dog).age)
res124: scala.math.Ordering[Dog] = scala.math.Ordering$$anon$3@fc6ef0
scala> implicitly[Equal[Int]] contramap ((_: Dog).age)
res126: scalaz.Equal[Dog] = scalaz.Equals$$anon$2@df06c2
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