From 37ad3c66baa2df36594277022dcf68fa8d4fff26 Mon Sep 17 00:00:00 2001
From: Jakob Odersky <jakob@odersky.com>
Date: Thu, 2 Aug 2018 15:42:22 -0700
Subject: Rename default type field to '@type'

---
 README.md                                            |  2 +-
 shared/src/main/scala/DerivedFormats.scala           |  2 +-
 shared/src/main/scala/annotations.scala              |  8 ++++----
 shared/src/test/scala/CoproductTypeFormatTests.scala | 16 ++++++++--------
 4 files changed, 14 insertions(+), 14 deletions(-)

diff --git a/README.md b/README.md
index 4148926..6e72b7f 100644
--- a/README.md
+++ b/README.md
@@ -70,7 +70,7 @@ object Main extends App {
 
   println(Seq[X](Z(Y(42), "foo"), Y(2)).toJson.prettyPrint)
   // [{
-  //   "type": "Z",
+  //   "@type": "Z",
   //   "y": {
   //     "x": 42
   //   },
diff --git a/shared/src/main/scala/DerivedFormats.scala b/shared/src/main/scala/DerivedFormats.scala
index ed39f46..7c13314 100644
--- a/shared/src/main/scala/DerivedFormats.scala
+++ b/shared/src/main/scala/DerivedFormats.scala
@@ -68,7 +68,7 @@ trait DerivedFormats { self: BasicFormats =>
       .collectFirst {
         case g: adt => g.typeFieldName
       }
-      .getOrElse("type")
+      .getOrElse("@type")
 
     new JsonFormat[T] {
       override def write(value: T): JsValue = ctx.dispatch(value) { sub =>
diff --git a/shared/src/main/scala/annotations.scala b/shared/src/main/scala/annotations.scala
index 4437aeb..ad2a37f 100644
--- a/shared/src/main/scala/annotations.scala
+++ b/shared/src/main/scala/annotations.scala
@@ -7,16 +7,16 @@ import scala.annotation.StaticAnnotation
   * added to the final JSON objects.
   *
   * Note that by default all sealed traits are treated as ADTs, with a type
-  * field called `type`. This annotation enables overriding the name of that
+  * field called `@type`. This annotation enables overriding the name of that
   * field and is really only useful if a child itself has a field called `type`
   * that would otherwise result in a conflict.
   *
   * Example:
   * {{{
   * // the JSON field "kind" will contain the actual type of the serialized child
-  * @adt("kind") sealed abstract class Keyword(`type`: String)
-  * case class If(`type`: String) extends Keyword(`type`)
+  * @adt("kind") sealed abstract class Keyword(`@type`: String)
+  * case class If(`@type`: String) extends Keyword(`@type`)
   * }}}
   * @param typeFieldName the name of the field to inject into a serialized JSON
   *        object */
-final class adt(val typeFieldName: String = "type") extends StaticAnnotation
+final class adt(val typeFieldName: String = "@type") extends StaticAnnotation
diff --git a/shared/src/test/scala/CoproductTypeFormatTests.scala b/shared/src/test/scala/CoproductTypeFormatTests.scala
index 7da2041..5e88856 100644
--- a/shared/src/test/scala/CoproductTypeFormatTests.scala
+++ b/shared/src/test/scala/CoproductTypeFormatTests.scala
@@ -18,33 +18,33 @@ class CoproductTypeFormatTests
 
   "No-parameter case class child" should behave like checkRoundtrip[Expr](
     Zero(),
-    """{"type":"Zero"}"""
+    """{"@type":"Zero"}"""
   )
 
   "Simple parameter case class child" should behave like checkRoundtrip[Expr](
     Value(42),
-    """{"type":"Value","x":42}"""
+    """{"@type":"Value","x":42}"""
   )
 
   "Nested parameter case class child" should behave like checkRoundtrip[Expr](
     Plus(Value(42), One),
-    """{"type":"Plus","lhs":{"type":"Value","x":42},"rhs":{"type":"One"}}"""
+    """{"@type":"Plus","lhs":{"@type":"Value","x":42},"rhs":{"@type":"One"}}"""
   )
 
   "Case object child" should behave like checkRoundtrip[Expr](
     One,
-    """{"type": "One"}"""
+    """{"@type": "One"}"""
   )
 
   @adt("kind")
-  sealed abstract class Keyword(`type`: String)
-  case class If(`type`: String) extends Keyword(`type`)
+  sealed abstract class Keyword(`@type`: String)
+  case class If(`@type`: String) extends Keyword(`@type`)
 
   implicit val keywordFormat: RootJsonFormat[Keyword] = jsonFormat[Keyword]
 
   "ADT with type field alias" should behave like checkRoundtrip[Keyword](
     If("class"),
-    """{"kind":"If","type":"class"}"""
+    """{"kind":"If","@type":"class"}"""
   )
 
   @adt("""_`crazy type!`"""")
@@ -68,7 +68,7 @@ class CoproductTypeFormatTests
 
   "Enum" should behave like checkRoundtrip[List[Enum]](
     A :: B :: Nil,
-    """[{"type":"A"}, {"type":"B"}]"""
+    """[{"@type":"A"}, {"@type":"B"}]"""
   )
 
   "Serializing as sealed trait and deserializing as child" should "work" in {
-- 
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