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author | Piotr Krzemiński <pio.krzeminski@gmail.com> | 2017-06-21 13:17:43 +0100 |
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committer | Piotr Krzemiński <pio.krzeminski@gmail.com> | 2017-06-21 13:20:49 +0100 |
commit | 2b4ef02a92e431b16d9b314def1da204fd1f9ab1 (patch) | |
tree | a948830efec3e573130e4dc037b3a3f46fce1efc /examples/src/main | |
parent | d1a7565a92d81a451c50d7739365d7106f63f1b7 (diff) | |
download | magnolia-2b4ef02a92e431b16d9b314def1da204fd1f9ab1.tar.gz magnolia-2b4ef02a92e431b16d9b314def1da204fd1f9ab1.tar.bz2 magnolia-2b4ef02a92e431b16d9b314def1da204fd1f9ab1.zip |
initial support for 2-arg contravariant derivations; works for simple Eq typeclass, still wip
Diffstat (limited to 'examples/src/main')
-rw-r--r-- | examples/src/main/scala/example.scala | 32 |
1 files changed, 31 insertions, 1 deletions
diff --git a/examples/src/main/scala/example.scala b/examples/src/main/scala/example.scala index e649b88..c649fba 100644 --- a/examples/src/main/scala/example.scala +++ b/examples/src/main/scala/example.scala @@ -14,13 +14,23 @@ object `package` { implicit val showBool: Show[Boolean] = _.toString implicit def showList[T: Show]: Show[List[T]] = xs => xs.map { x => s"list:${implicitly[Show[T]].show(x)}" }.mkString(";") implicit def showSet[T: Show]: Show[Set[T]] = s => "set" + + implicit class Equable[T: Eq](t: T) { + def isEqualTo(other: T): Boolean = implicitly[Eq[T]].isEqual(t, other) + } + implicit val eqString: Eq[String] = _ == _ + implicit val eqBool: Eq[Boolean] = _ == _ + implicit def eqList[T: Eq]: Eq[List[T]] = + (l1, l2) => l1.size == l2.size && (l1 zip l2).forall { case (e1, e2) => e1 isEqualTo e2 } + implicit def eqSet[T: Eq]: Eq[Set[T]] = + (s1, s2) => s1.size == s2.size && (s1 zip s2).forall { case (e1, e2) => e1 isEqualTo e2 } } sealed trait EmptyType sealed trait Tree case class Branch(left: Tree, right: Tree) extends Tree -case class Leaf(value: Int, no: EmptyType) extends Tree +case class Leaf(value: Int, no: String) extends Tree sealed trait Entity case class Person(name: String, address: Address) extends Entity @@ -42,3 +52,23 @@ object Show extends Show_1 { trait Show_1 { implicit def generic[T]: Show[T] = macro Macros.magnolia[T, Show[_]] } + +trait Eq[T] { def isEqual(a: T, b: T): Boolean } + +object Eq extends Eq_1 { + + implicit val eqInt: Eq[Int] = _ == _ + + implicit val derivation = new ContravariantDerivation2[Eq] { + type Return = Boolean + def call[T](eq: Eq[T], value1: T, value2: T): Boolean = + if(value1.getClass == value2.getClass) eq.isEqual(value1, value2) else false + def construct[T](body: (T, T) => Boolean): Eq[T] = body(_, _) + def join(elements: ListMap[String, Boolean]): Boolean = elements.forall(_._2) + } +} + +trait Eq_1 { + implicit def generic[T]: Eq[T] = macro Macros.magnolia[T, Eq[_]] +} + |