Add tailOption for std List

scalaz · Apr 19, 2014 · cfcdda8 · cfcdda8
1 parent a4db99e
commit cfcdda8
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diff --git a/core/src/main/scala/scalaz/std/List.scala b/core/src/main/scala/scalaz/std/List.scala
@@ -136,6 +136,11 @@ trait ListFunctions {
     intersperse0(Nil, as).reverse
   }
 
+  final def tailOption[A](as: List[A]): Option[List[A]] = as match {
+    case Nil    => None
+    case _ :: t => Some(t)
+  }
+
   /** [[scala.Nil]] with a sometimes more convenient type */
   final def nil[A]: List[A] = Nil
 

diff --git a/core/src/main/scala/scalaz/syntax/std/ListOps.scala b/core/src/main/scala/scalaz/syntax/std/ListOps.scala
@@ -8,6 +8,8 @@ import scalaz.std.{list => l}
 final class ListOps[A](self: List[A]) {
   final def intersperse(a: A): List[A] = l.intersperse(self, a)
 
+  final def tailOption: Option[List[A]] = l.tailOption(self)
+
   final def toNel: Option[NonEmptyList[A]] = l.toNel(self)
 
   final def toZipper: Option[Zipper[A]] = l.toZipper(self)