ToJson instances for Either (#48)

ninny/src/nrktkt/ninny/ToJsonInstances.scala

@@ -57,9 +57,14 @@ trait ToJsonInstances
 
   implicit val noneToJson: ToJson[None.type]          = _ => None
   implicit def someToJson[A: ToJson]: ToJson[Some[A]] = optionToJson[A].to(_)
-  implicit def someToSomeJson[A: ToSomeJson]: ToSomeJson[Some[A]] =
+  implicit def someToSomeJson[A: ToSomeJson]: ToSomeJson[Some[A]] = 
     _.value.toSomeJson
 
+  implicit def leftToJson[L: ToJson, R]: ToJson[Left[L, R]] = _.value.toJson
+  implicit def rightToJson[L, R: ToJson]: ToJson[Right[L, R]] = _.value.toJson
+  implicit def eitherToJson[L: ToJson, R: ToJson]: ToJson[Either[L, R]] = 
+    _.fold(_.toJson, _.toJson)
+
   implicit val instantToJson: ToSomeJson[Instant] =
     i => JsonNumber(i.getEpochSecond.toDouble)
 

ninny/test/src/nrktkt/ninny/ToJsonInstancesSpec.scala

@@ -0,0 +1,25 @@
+package nrktkt.ninny
+
+import org.scalatest._
+import org.scalatest.flatspec._
+import org.scalatest.matchers._
+import io.github.kag0.ninny.ast._
+
+class ToJsonInstancesSpec extends AnyFlatSpec with should.Matchers {
+  "Either values" should 
+    "convert right to json" in {
+      val right = Right[Int, String]("test")
+      val either: Either[Int, String] = right
+      val expected = Some(JsonString("test"))
+      right.toJson shouldEqual expected
+      either.toJson shouldEqual expected
+    }
+
+    it should "convert left to json" in {
+      val left = Left[Int, String](5)
+      val either: Either[Int, String] = left
+      val expected = Some(JsonNumber(5))
+      left.toJson shouldEqual expected
+      either.toJson shouldEqual expected
+    }
+}