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channingwalton/FirstSome.scala

Last active December 14, 2015 14:58
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Iterate a list of functions A => Option[B] returning the first Some
Raw
FirstSome.scala
object play {
import scalaz._
import Scalaz._
def foo(i: Int) = if (i > 0) Some(i) else None
def boo(i: Int) = if (i <= 0) Some(0) else None
val l = foo _ :: boo _ :: Nil
l.foldMap(_.map(_.first)) apply -1
//> res0: scalaz.@@[Option[Int],scalaz.Tags.First] = Some(0)
}
@bmjames
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bmjames commented Mar 7, 2013

Nicely done. Purely to demonstrate that a new function is being produced (using the derived monoid as explained by Rahul), I might assign the result of the foldMap to a value and then apply it with normal parens syntax.

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