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-rw-r--r--examples/src/main/scala/default.scala24
1 files changed, 24 insertions, 0 deletions
diff --git a/examples/src/main/scala/default.scala b/examples/src/main/scala/default.scala
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+++ b/examples/src/main/scala/default.scala
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+package magnolia.examples
+
+import scala.language.existentials
+import scala.language.higherKinds
+
+import magnolia._
+import scala.language.experimental.macros
+
+trait Default[T] { def default: T }
+
+object Default {
+ type Typeclass[T] = Default[T]
+ def join[T](ctx: JoinContext[Default, T]): Default[T] = new Default[T] {
+ def default = ctx.construct { param => param.typeclass.default }
+ }
+
+ def dispatch[T](ctx: DispatchContext[Default, T])(): Default[T] = new Default[T] {
+ def default: T = ctx.subtypes.head.typeclass.default
+ }
+
+ implicit val string: Default[String] = new Default[String] { def default = "" }
+ implicit val int: Default[Int] = new Default[Int] { def default = 0 }
+ implicit def generic[T]: Default[T] = macro Magnolia.generic[T]
+}