API improvements and better examples

1 files changed, 25 insertions, 0 deletions

diff --git a/examples/src/main/scala/eq.scala b/examples/src/main/scala/eq.scala
new file mode 100644
index 0000000..ec9be14
--- /dev/null
+++ b/examples/src/main/scala/eq.scala
@@ -0,0 +1,25 @@
+package magnolia.examples
+
+import scala.language.higherKinds
+
+import magnolia._
+import scala.language.experimental.macros
+
+trait Eq[T] { def equal(value: T, value2: T): Boolean }
+
+object Eq {
+  type Typeclass[T] = Eq[T]
+  def join[T](ctx: JoinContext[Eq, T]): Eq[T] = new Eq[T] {
+    def equal(value1: T, value2: T) =
+      ctx.parameters.forall { param => param.typeclass.equal(param.dereference(value1), param.dereference(value2)) }
+  }
+
+  def dispatch[T](ctx: DispatchContext[Eq, T]): Eq[T] = new Eq[T] {
+    def equal(value1: T, value2: T): Boolean =
+      ctx.dispatch(value1) { case sub => sub.typeclass.equal(sub.cast(value1), sub.cast(value2)) }
+  }
+
+  implicit val string: Eq[String] = new Eq[String] { def equal(v1: String, v2: String) = v1 == v2 }
+  implicit val int: Eq[Int] = new Eq[Int] { def equal(v1: Int, v2: Int) = v1 == v2 }
+  implicit def generic[T]: Eq[T] = macro Magnolia.generic[T]
+}