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Diffstat (limited to 'examples/src/main/scala/default.scala')
-rw-r--r-- | examples/src/main/scala/default.scala | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/examples/src/main/scala/default.scala b/examples/src/main/scala/default.scala new file mode 100644 index 0000000..1f602f9 --- /dev/null +++ b/examples/src/main/scala/default.scala @@ -0,0 +1,24 @@ +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] +} |