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Diffstat (limited to 'examples/src/main/scala/cats.scala')
-rw-r--r-- | examples/src/main/scala/cats.scala | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/examples/src/main/scala/cats.scala b/examples/src/main/scala/cats.scala new file mode 100644 index 0000000..8d33a0f --- /dev/null +++ b/examples/src/main/scala/cats.scala @@ -0,0 +1,22 @@ +package magnolia.examples + +import scala.collection.immutable.ListMap +import scala.language.experimental.macros + +import cats.Show +import magnolia.ContravariantDerivation +import magnolia.Macros + +object catsShowDerivation { + + implicit val showDerivation: ContravariantDerivation[Show] = + new ContravariantDerivation[Show] { + type Return = String + def call[T](show: Show[T], value: T): String = show.show(value) + def construct[T](body: T => String): Show[T] = body(_) + def join(xs: ListMap[String, String]): String = + xs.map { case (k, v) => s"$k=$v" }.mkString("{", ", ", "}") + } + + implicit def genericShow[T]: Show[T] = macro Macros.magnolia[T, Show[_]] +} |