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seanparsons/FirstSome.scala

Forked from channingwalton/FirstSome.scala
Last active December 14, 2015 15:19
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Cunning use of monoids with Function1.
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FirstSome.scala
scala> import scalaz._,Scalaz._
import scalaz._
import Scalaz._
scala> val isOne = (i: Int) => {println("isOne"); if (i == 1) Some(1) else None}
isOne: Int => Option[Int] = <function1>
scala> val isTwo = (i: Int) => {println("isTwo"); if (i == 2) Some(2) else None}
isTwo: Int => Option[Int] = <function1>
scala> List(isOne, isTwo).foldMap(check => check(2).first)
isOne
isTwo
res2: scalaz.package.@@[Option[Int],scalaz.Tags.First] = Some(2)
scala> List(isOne, isTwo).foldMap(check => check(1).first)
isOne
res3: scalaz.package.@@[Option[Int],scalaz.Tags.First] = Some(1)
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