Add appendable to Basics (#168)

morphir/sdk/core/src/morphir/sdk/Appendable.scala

@@ -0,0 +1,32 @@
+package morphir.sdk
+
+/// Type class for appending two values of the same type.
+trait Appendable[A] {
+  def append(a: A, b: A): A
+}
+
+object Appendable extends LowerPriorityAppendable {
+  def apply[A](implicit appendable: Appendable[A]): Appendable[A] = appendable
+
+  implicit val stringAppendable: Appendable[String] = new Appendable[String] {
+    override def append(a: String, b: String): String = a + b
+  }
+
+  implicit def listAppendable[A]: Appendable[List[A]] = new Appendable[List[A]] {
+    override def append(a: List[A], b: List[A]): List[A] = a ++ b
+  }
+
+  implicit def vectorAppendable[A]: Appendable[Vector[A]] = new Appendable[Vector[A]] {
+    override def append(a: Vector[A], b: Vector[A]): Vector[A] = a ++ b
+  }
+
+  implicit def setAppendable[A]: Appendable[Set[A]] = new Appendable[Set[A]] {
+    override def append(a: Set[A], b: Set[A]): Set[A] = a ++ b
+  }
+}
+
+trait LowerPriorityAppendable {
+  implicit def iterableAppendable[A]: Appendable[Iterable[A]] = new Appendable[Iterable[A]] {
+    override def append(a: Iterable[A], b: Iterable[A]): Iterable[A] = a ++ b
+  }
+}

morphir/sdk/core/src/morphir/sdk/Basics.scala

@@ -16,7 +16,11 @@ limitations under the License.
 
 package morphir.sdk
 
-object Basics {
+trait Basics {
+  def append[A: Appendable](a: A)(b: A): A = Appendable[A].append(a, b)
+}
+
+object Basics extends Basics {
 
   sealed abstract class Order(val value: Int) extends Product with Serializable
   object Order {

morphir/sdk/core/src/morphir/sdk/Set.scala

@@ -19,7 +19,7 @@ import morphir.sdk.Basics.Bool
 
 object Set {
   type Set[A] = scala.collection.immutable.Set[A]
-  private val Set = scala.collection.immutable.Set
+  private[morphir] val Set = scala.collection.immutable.Set
 
   /** Create an empty set.
     */

morphir/sdk/core/test/src/morphir/sdk/AppendableSpec.scala

@@ -0,0 +1,44 @@
+package morphir.sdk
+
+import morphir.testing.MorphirBaseSpec
+
+import zio.test.Assertion._
+import zio.test._
+import morphir.testing.MorphirBaseSpec
+
+object AppendableSpec extends MorphirBaseSpec {
+  def spec = suite("AppendableSpec")(
+    suite("Appendable.append spec")(
+      test("Appending two strings") {
+        val a        = "Hello, "
+        val b        = "World!"
+        val expected = "Hello, World!"
+        assert(morphir.sdk.Basics.append(a)(b))(equalTo(expected))
+      },
+      test("Appending two lists") {
+        val a        = List(1, 2, 3)
+        val b        = List(4, 5, 6)
+        val expected = List(1, 2, 3, 4, 5, 6)
+        assert(morphir.sdk.Basics.append(a)(b))(equalTo(expected))
+      },
+      test("Appending two sets") {
+        val a        = morphir.sdk.Set.Set(1, 2, 3)
+        val b        = morphir.sdk.Set.Set(4, 5, 6)
+        val expected = morphir.sdk.Set.Set(1, 2, 3, 4, 5, 6)
+        assert(morphir.sdk.Basics.append(a)(b))(equalTo(expected))
+      },
+      test("Appending two iterables") {
+        val a        = Iterable(1, 2, 3)
+        val b        = Iterable(4, 5, 6)
+        val expected = Iterable(1, 2, 3, 4, 5, 6)
+        assert(morphir.sdk.Basics.append(a)(b))(equalTo(expected))
+      },
+      test("Appending two vectors") {
+        val a        = Vector(1, 2, 3)
+        val b        = Vector(4, 5, 6)
+        val expected = Vector(1, 2, 3, 4, 5, 6)
+        assert(morphir.sdk.Basics.append(a)(b))(equalTo(expected))
+      }
+    )
+  )
+}