Added readOption and readOrElse to YamlSequence

src/main/scala/shampoo/yaml/YamlNode.scala

@@ -509,6 +509,34 @@ sealed trait YamlSequence extends YamlCollection:
       case YamlNull => throw NullPointerException()
       case node     => node.as[T]
 
+  /**
+   * Optionally reads constructed data.
+   *
+   * @param index sequence index
+   * @param constructor data constructor
+   *
+   * @return `Some` constructed data, or `None` if node is null
+   *
+   * @throws java.lang.IndexOutOfBoundsException if index is out of bounds
+   */
+  def readOption[T](index: Int)(using constructor: YamlConstructor[T]): Option[T] =
+    apply(index) match
+      case YamlNull => None
+      case node     => Some(node.as[T])
+
+  /**
+   * Reads constructed data or returns default value.
+   *
+   * @param index sequence index
+   * @param constructor data constructor
+   *
+   * @return constructed data, or default value if node is null
+   *
+   * @throws java.lang.IndexOutOfBoundsException if index is out of bounds
+   */
+  def readOrElse[T](index: Int, default: => T)(using constructor: YamlConstructor[T]): T =
+    readOption(index).getOrElse(default)
+
 /**
  * Assumes either YAML mapping or YAML sequence.
  *

src/test/scala/shampoo/yaml/YamlSpec.scala

@@ -124,6 +124,33 @@ class YamlSpec extends org.scalatest.flatspec.AnyFlatSpec:
     verify(copy)
   }
 
+  it should "read optional sequence values" in {
+    val yaml = Yaml.seq(
+      YamlString("abc"),
+      YamlNumber(123),
+      YamlBoolean(true),
+      YamlNull
+    )
+
+    assert { yaml.read[String](0) == "abc" }
+    assert { yaml.readOption[String](0) == Some("abc") }
+    assert { yaml.readOrElse(0, "def") == "abc" }
+
+    assert { yaml.read[Int](1) == 123 }
+    assert { yaml.readOption[Int](1) == Some(123) }
+    assert { yaml.readOrElse(1, 456) == 123 }
+
+    assert { yaml.read[Boolean](2) == true }
+    assert { yaml.readOption[Boolean](2) == Some(true) }
+    assert { yaml.readOrElse(2, false) }
+
+    assert { yaml(3) == YamlNull }
+
+    assertThrows[NullPointerException] { yaml.read[String](3) }
+    assert { yaml.readOption[String](3) == None }
+    assert { yaml.readOrElse(3, "def") == "def" }
+  }
+
   private def verify(yaml: YamlMapping): Unit =
     assert(yaml.nonEmpty)
     assert(yaml.size == 7)