API improvements and better examples

1 files changed, 26 insertions, 0 deletions

diff --git a/examples/src/main/scala/show.scala b/examples/src/main/scala/show.scala
new file mode 100644
index 0000000..9af828e
--- /dev/null
+++ b/examples/src/main/scala/show.scala
@@ -0,0 +1,26 @@
+package magnolia.examples
+
+import scala.language.existentials
+import scala.language.higherKinds
+
+import magnolia._
+import scala.language.experimental.macros
+
+trait Show[Out, T] { def show(value: T): Out }
+
+object Show {
+  type Typeclass[T] = Show[String, T]
+  def join[T](ctx: JoinContext[Typeclass, T]): Show[String, T] = new Show[String, T] {
+    def show(value: T) = ctx.parameters.map { param =>
+      s"${param.label}=${param.typeclass.show(param.dereference(value))}"
+    }.mkString(s"${ctx.typeName.split("\\.").last}(", ",", ")")
+  }
+
+  def dispatch[T](ctx: DispatchContext[Typeclass, T]): Show[String, T] = new Show[String, T] {
+    def show(value: T): String = ctx.dispatch(value) { sub => sub.typeclass.show(sub.cast(value)) }
+  }
+
+  implicit val string: Show[String, String] = new Show[String, String] { def show(s: String): String = s }
+  implicit val int: Show[String, Int] = new Show[String, Int] { def show(s: Int): String = s.toString }
+  implicit def generic[T]: Show[String, T] = macro Magnolia.generic[T]
+}