feat: Added the Raise effect (very tiny extract from the Raise4s libr…

…ary)

yaes-core/src/main/scala/in/rcard/yaes/Raise.scala

@@ -0,0 +1,32 @@
+package in.rcard.yaes
+
+import scala.util.control.{ControlThrowable, NoStackTrace}
+
+trait TypedError[-E] {
+  def raise(error: E): Nothing
+}
+
+type Raise[E] = Effect[TypedError[E]]
+
+private[yaes] case class Raised[E](original: E)
+extends ControlThrowable
+  with NoStackTrace
+
+private[yaes] class DefaultTypedError extends TypedError[Any]:
+  def raise(e: Any): Nothing = throw Raised(e)
+
+object Raise {
+  def apply[E, A](block: => A): Raise[E] ?=> A = block
+
+  def raise[E](error: E)(using eff: Raise[E]): Nothing = eff.sf.raise(error)
+
+  def run[E, A](block: Raise[E] ?=> A): A | E = {
+    given eff: Effect[TypedError[E]] = new Effect(new DefaultTypedError)
+
+    try {
+      block(using eff)
+    } catch {
+      case Raised(e) => e.asInstanceOf[E]
+    }
+  }
+}

yaes-core/src/test/scala/in/rcard/yaes/RaiseSpec.scala

@@ -0,0 +1,47 @@
+package in.rcard.yaes
+
+import org.scalatest.flatspec.AnyFlatSpec
+import org.scalatest.matchers.should.Matchers
+
+class RaiseSpec extends AnyFlatSpec with Matchers {
+
+  "Raise effect" should "be able to raise a typed error" in {
+    val actualResult = Raise.run {
+      Raise {
+        Raise.raise("Error")
+      }
+    }
+
+    actualResult shouldBe "Error"
+  }
+
+  it should "be able to run a block that does not raise an error" in {
+    val actualResult = Raise.run {
+      Raise {
+        42
+      }
+    }
+
+    actualResult shouldBe 42
+  }
+
+  it should "not catch exceptions" in {
+    assertThrows[RuntimeException] {
+      Raise.run {
+        Raise { throw new RuntimeException("Boom!") }
+      }
+    }
+  }
+
+  it should "compose with other effects" in {
+    val actualResult: (Effect[SideEffect], Raise[String]) ?=> Int = for {
+      io <- IO { 42 }
+      result <- Raise {
+        if (io != 42) io
+        else Raise.raise("Boom!")
+      }
+    } yield result
+
+    IO.run { Raise.run { actualResult } } shouldBe "Boom!"
+  }
+}