Merge pull request #97 from road21/option-either-functions

add option/either functions
tofu-tf · Jan 9, 2020 · 5c66362 · 5c66362
2 parents 143788c + a4564cf
commit 5c66362
Showing 1 changed file with 9 additions and 0 deletions.
diff --git a/optics/core/src/main/scala/tofu/optics/functions.scala b/optics/core/src/main/scala/tofu/optics/functions.scala
@@ -2,6 +2,7 @@ package tofu.optics
 
 import cats.Apply
 import cats.syntax.apply._
+import cats.syntax.either._
 import cats.instances.all._
 import alleycats.std.map._
 
@@ -47,4 +48,12 @@ object functions {
 
   def everyTuple4[A, B]: PItems[(A, A, A, A), (B, B, B, B), A, B] =
     PItems[(A, A, A, A), A, B](implicit A => (s, f) => (f(s._1), f(s._2), f(s._3), f(s._4)).tupled)
+
+  def right[A, B]: Subset[Either[A, B], B] = Subset[Either[A, B]](_.toOption)(_.asRight)
+
+  def left[A, B]: Subset[Either[A, B], A] = Subset[Either[A, B]](_.fold(Some(_), _ => None))(_.asLeft)
+
+  def some[A]: Subset[Option[A], A] = Subset[Option[A]](identity)(Some(_))
+
+  def none[A]: Subset[Option[A], Unit] = Subset[Option[A]](_ => Some(()))(_ => None)
 }