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Diffstat (limited to 'examples/src/main/scala/eq.scala')
-rw-r--r-- | examples/src/main/scala/eq.scala | 50 |
1 files changed, 50 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..30e7869 --- /dev/null +++ b/examples/src/main/scala/eq.scala @@ -0,0 +1,50 @@ +package magnolia.examples + +import magnolia._ + +import language.experimental.macros +import collection.immutable.ListMap + +object `package` { + 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 Tree +case class Branch(left: Tree, right: Tree) extends Tree +case class Leaf(value: Int) extends Tree + +sealed trait Entity +case class Person(name: String, address: Address) extends Entity +case class Organization(name: String, contacts: Set[Person]) extends Entity +case class Address(lines: List[String], country: Country) +case class Country(name: String, code: String, salesTax: Boolean) + +trait Eq[T] { def isEqual(a: T, b: T): Boolean } + +object Eq { + + implicit val eqInt: Eq[Int] = _ == _ + + implicit val derivation: ContravariantDerivation2[Eq] = 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) + } + + implicit def generic[T]: Eq[T] = macro Macros.magnolia[T, Eq[_]] +} |