Added the 'value' function for the List[Either[E, A]] type

README.md

@@ -254,6 +254,13 @@ val three = Raise.either {
 
 The `value` function calls the `raise` function if the `Either` instance is a `Left`; otherwise, it returns the value wrapped by the `Right` instance. Despite the trivial logic implemented in the above example, it's a good example of how to compose functions that return an `Either[E, A]` using the Raise DSL without the use of any `flatMap` function.
 
+A useful shortcut is available when we need to transform a `List[Either[E, A]]` into a `List[A] raises E`. The eventual raised error `E` is the first error found in the list of `Either[E, A]`:
+
+```scala 3
+val eitherList: List[Either[String, Int]] = List(Right(1), Left("error"), Right(3))
+val raiseList: List[Int] raises String = listWithError.value
+```
+
 Be aware that before version 0.0.5, the `value` function was called `bind()`.
 
 We can do the same with `Try[A]` and `Option[A]` using the `asTry` and `option` builders, respectively. Let's start with the `asTry` builder. In this case, the only available type of error is `Throwable`:

src/main/scala/in/rcard/raise4s/Bind.scala

@@ -9,6 +9,9 @@ object Bind {
       case Right(value) => value
       case Left(error)  => Raise.raise(error)
     }
+
+  extension [Error, A](list: List[Either[Error, A]])
+    def value(using Raise[Error]): List[A] = list.map(_.value)
 
   extension [A](option: Option[A])
     def value(using Raise[None.type]): A = option match {

src/test/scala/in/rcard/raise4s/BindTest.scala

@@ -46,4 +46,17 @@ class BindTest extends AnyFlatSpec with Matchers {
 
     actual should be(Success(2))
   }
+
+  "List[Either[Error, A]].value" should "return a value if the list doesn't contain errors and raise an error otherwise" in {
+    val list: List[Either[String, Int]] = List(Right(1), Right(2), Right(3))
+    val listWithError: List[Either[String, Int]] = List(Right(1), Left("error"), Right(3))
+
+    val actual = Raise.either {
+      val x = list.value
+      val y = recover({ listWithError.value }) { _ => List(1) }
+      x.sum + y.sum
+    }
+
+    actual should be(Right(7))
+  }
 }