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davidandrzej/key-union.scala

Created October 31, 2013 19:37
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Get union of all keys from a collection of Maps, the scalaz way.
Raw
key-union.scala
import scalaz._, Scalaz._
val data = Vector(Map(1 -> "a", 2 -> "b"), Map(2 -> "c", 3 -> "d"))
data.foldMap(_.keys.toSet)
// res0: scala.collection.immutable.Set[Int] = Set(1, 2, 3)
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