Errors smithy4s

build.sbt

@@ -40,6 +40,14 @@ val commonSettings = Seq(
       case Some((2, _)) => Seq(s"-target:jvm-$jdkVersion")
       case _            => Seq(s"-java-output-version:$jdkVersion")
     }
+  },
+  bspEnabled := {
+    val id = thisProjectRef.value.project
+    val isScala3 = scalaVersion.value.startsWith("3.")
+    val isJS = id.contains("JS")
+    val isNative = id.contains("Native")
+
+    isScala3 && !isJS && !isNative
   }
 )
 

modules/core/src/main/scala/jsonrpclib/Endpoint.scala

@@ -1,9 +1,12 @@
 package jsonrpclib
 
 import io.circe.Codec
+import jsonrpclib.ErrorCodec.errorPayloadCodec
 
 sealed trait Endpoint[F[_]] {
   def method: String
+
+  def mapK[G[_]](f: F ~> G): Endpoint[G]
 }
 
 object Endpoint {
@@ -16,20 +19,20 @@ object Endpoint {
   class PartiallyAppliedEndpoint[F[_]](method: MethodPattern) {
     def apply[In, Err, Out](
         run: In => F[Either[Err, Out]]
-    )(implicit inCodec: Codec[In], errCodec: ErrorCodec[Err], outCodec: Codec[Out]): Endpoint[F] =
-      RequestResponseEndpoint(method, (_: InputMessage, in: In) => run(in), inCodec, errCodec, outCodec)
+    )(implicit inCodec: Codec[In], errEncoder: ErrorEncoder[Err], outCodec: Codec[Out]): Endpoint[F] =
+      RequestResponseEndpoint(method, (_: InputMessage, in: In) => run(in), inCodec, errEncoder, outCodec)
 
     def full[In, Err, Out](
         run: (InputMessage, In) => F[Either[Err, Out]]
-    )(implicit inCodec: Codec[In], errCodec: ErrorCodec[Err], outCodec: Codec[Out]): Endpoint[F] =
-      RequestResponseEndpoint(method, run, inCodec, errCodec, outCodec)
+    )(implicit inCodec: Codec[In], errEncoder: ErrorEncoder[Err], outCodec: Codec[Out]): Endpoint[F] =
+      RequestResponseEndpoint(method, run, inCodec, errEncoder, outCodec)
 
     def simple[In, Out](
         run: In => F[Out]
     )(implicit F: Monadic[F], inCodec: Codec[In], outCodec: Codec[Out]) =
       apply[In, ErrorPayload, Out](in =>
         F.doFlatMap(F.doAttempt(run(in))) {
-          case Left(error)  => F.doPure(Left(ErrorPayload(0, error.getMessage(), None)))
+          case Left(error)  => F.doPure(Left(ErrorPayload(-32000, error.getMessage(), None)))
           case Right(value) => F.doPure(Right(value))
         }
       )
@@ -42,18 +45,25 @@ object Endpoint {
 
   }
 
-  final case class NotificationEndpoint[F[_], In](
+  private[jsonrpclib] final case class NotificationEndpoint[F[_], In](
       method: MethodPattern,
       run: (InputMessage, In) => F[Unit],
       inCodec: Codec[In]
-  ) extends Endpoint[F]
+  ) extends Endpoint[F] {
+
+    def mapK[G[_]](f: F ~> G): Endpoint[G] =
+      NotificationEndpoint[G, In](method, (msg, in) => f(run(msg, in)), inCodec)
+  }
 
-  final case class RequestResponseEndpoint[F[_], In, Err, Out](
+  private[jsonrpclib] final case class RequestResponseEndpoint[F[_], In, Err, Out](
       method: Method,
       run: (InputMessage, In) => F[Either[Err, Out]],
       inCodec: Codec[In],
-      errCodec: ErrorCodec[Err],
+      errEncoder: ErrorEncoder[Err],
       outCodec: Codec[Out]
-  ) extends Endpoint[F]
+  ) extends Endpoint[F] {
 
+    def mapK[G[_]](f: F ~> G): Endpoint[G] =
+      RequestResponseEndpoint[G, In, Err, Out](method, (msg, in) => f(run(msg, in)), inCodec, errEncoder, outCodec)
+  }
 }

modules/core/src/main/scala/jsonrpclib/ErrorCodec.scala

@@ -1,12 +1,15 @@
 package jsonrpclib
 
-trait ErrorCodec[E] {
-
+trait ErrorEncoder[E] {
   def encode(a: E): ErrorPayload
-  def decode(error: ErrorPayload): Either[ProtocolError, E]
+}
 
+trait ErrorDecoder[E] {
+  def decode(error: ErrorPayload): Either[ProtocolError, E]
 }
 
+trait ErrorCodec[E] extends ErrorDecoder[E] with ErrorEncoder[E]
+
 object ErrorCodec {
   implicit val errorPayloadCodec: ErrorCodec[ErrorPayload] = new ErrorCodec[ErrorPayload] {
     def encode(a: ErrorPayload): ErrorPayload = a

modules/core/src/main/scala/jsonrpclib/Monadic.scala

@@ -26,4 +26,19 @@ object Monadic {
 
     override def doMap[A, B](fa: Future[A])(f: A => B): Future[B] = fa.map(f)
   }
+
+  object syntax {
+    implicit class MonadicOps[F[_], A](fa: F[A]) {
+      def flatMap[B](f: A => F[B])(implicit m: Monadic[F]): F[B] = m.doFlatMap(fa)(f)
+      def map[B](f: A => B)(implicit m: Monadic[F]): F[B] = m.doMap(fa)(f)
+      def attempt[B](implicit m: Monadic[F]): F[Either[Throwable, A]] = m.doAttempt(fa)
+      def void(implicit m: Monadic[F]): F[Unit] = m.doVoid(fa)
+    }
+    implicit class MonadicOpsPure[A](a: A) {
+      def pure[F[_]](implicit m: Monadic[F]): F[A] = m.doPure(a)
+    }
+    implicit class MonadicOpsThrowable(t: Throwable) {
+      def raiseError[F[_], A](implicit m: Monadic[F]): F[A] = m.doRaiseError(t)
+    }
+  }
 }

modules/core/src/main/scala/jsonrpclib/PolyFunction.scala

@@ -0,0 +1,5 @@
+package jsonrpclib
+
+private[jsonrpclib] trait PolyFunction[F[_], G[_]] { self =>
+  def apply[A0](fa: F[A0]): G[A0]
+}

modules/core/src/main/scala/jsonrpclib/internals/FutureBaseChannel.scala

@@ -7,7 +7,6 @@ import scala.concurrent.ExecutionContext
 import scala.concurrent.Future
 import scala.concurrent.Promise
 import scala.util.Try
-import io.circe.Codec
 import io.circe.Encoder
 
 abstract class FutureBasedChannel(endpoints: List[Endpoint[Future]])(implicit ec: ExecutionContext)

modules/core/src/main/scala/jsonrpclib/internals/MessageDispatcher.scala

@@ -30,13 +30,13 @@ private[jsonrpclib] abstract class MessageDispatcher[F[_]](implicit F: Monadic[F
 
   def stub[In, Err, Out](
       method: String
-  )(implicit inCodec: Codec[In], errCodec: ErrorCodec[Err], outCodec: Codec[Out]): In => F[Either[Err, Out]] = {
+  )(implicit inCodec: Codec[In], errDecoder: ErrorDecoder[Err], outCodec: Codec[Out]): In => F[Either[Err, Out]] = {
     (input: In) =>
       val encoded = inCodec(input)
       doFlatMap(nextCallId()) { callId =>
         val message = InputMessage.RequestMessage(method, callId, Some(Payload(encoded)))
         doFlatMap(createPromise[Either[Err, Out]](callId)) { case (fulfill, future) =>
-          val pc = createPendingCall(errCodec, outCodec, fulfill)
+          val pc = createPendingCall(errDecoder, outCodec, fulfill)
           doFlatMap(storePendingCall(callId, pc))(_ => doFlatMap(sendMessage(message))(_ => future()))
         }
       }
@@ -85,7 +85,7 @@ private[jsonrpclib] abstract class MessageDispatcher[F[_]](implicit F: Monadic[F
                 val responseData = ep.outCodec(data)
                 sendMessage(OutputMessage.ResponseMessage(callId, Payload(responseData)))
               case Left(error) =>
-                val errorPayload = ep.errCodec.encode(error)
+                val errorPayload = ep.errEncoder.encode(error)
                 sendMessage(OutputMessage.ErrorMessage(callId, errorPayload))
             }
           case Left(pError) =>
@@ -111,13 +111,13 @@ private[jsonrpclib] abstract class MessageDispatcher[F[_]](implicit F: Monadic[F
   }
 
   private def createPendingCall[Err, Out](
-      errCodec: ErrorCodec[Err],
+      errDecoder: ErrorDecoder[Err],
       outCodec: Codec[Out],
       fulfill: Try[Either[Err, Out]] => F[Unit]
   ): OutputMessage => F[Unit] = { (message: OutputMessage) =>
     message match {
       case ErrorMessage(_, errorPayload) =>
-        errCodec.decode(errorPayload) match {
+        errDecoder.decode(errorPayload) match {
           case Left(_)      => fulfill(scala.util.Failure(errorPayload))
           case Right(value) => fulfill(scala.util.Success(Left(value)))
         }

modules/core/src/main/scala/jsonrpclib/package.scala

@@ -3,4 +3,6 @@ package object jsonrpclib {
   type ErrorCode = Int
   type ErrorMessage = String
 
+  private[jsonrpclib] type ~>[F[_], G[_]] = jsonrpclib.PolyFunction[F, G]
+
 }

modules/smithy4s/src/main/scala/jsonrpclib/smithy4sinterop/ServerEndpoints.scala

@@ -5,8 +5,13 @@ import jsonrpclib.Endpoint
 import smithy4s.Service
 import smithy4s.kinds.FunctorAlgebra
 import smithy4s.kinds.FunctorInterpreter
+import smithy4s.schema.Schema
 import jsonrpclib.Monadic
+import jsonrpclib.Payload
+import jsonrpclib.ErrorPayload
 import io.circe.Codec
+import jsonrpclib.Monadic.syntax._
+import jsonrpclib.ErrorEncoder
 
 object ServerEndpoints {
 
@@ -24,7 +29,6 @@ object ServerEndpoints {
     }
   }
 
-  // TODO : codify errors at smithy level and handle them.
   def jsonRPCEndpoint[F[_]: Monadic, Op[_, _, _, _, _], I, E, O, SI, SO](
       smithy4sEndpoint: Smithy4sEndpoint[Op, I, E, O, SI, SO],
       endpointSpec: EndpointSpec,
@@ -34,17 +38,38 @@ object ServerEndpoints {
     implicit val inputCodec: Codec[I] = CirceJson.fromSchema(smithy4sEndpoint.input)
     implicit val outputCodec: Codec[O] = CirceJson.fromSchema(smithy4sEndpoint.output)
 
+    def errorResponse(throwable: Throwable): F[E] = throwable match {
+      case smithy4sEndpoint.Error((_, e)) => e.pure
+      case e: Throwable                   => e.raiseError
+    }
+
     endpointSpec match {
       case EndpointSpec.Notification(methodName) =>
         Endpoint[F](methodName).notification { (input: I) =>
           val op = smithy4sEndpoint.wrap(input)
-          Monadic[F].doVoid(impl(op))
+          impl(op).void
         }
       case EndpointSpec.Request(methodName) =>
-        Endpoint[F](methodName).simple { (input: I) =>
-          val op = smithy4sEndpoint.wrap(input)
-          impl(op)
+        smithy4sEndpoint.error match {
+          case None =>
+            Endpoint[F](methodName).simple[I, O] { (input: I) =>
+              val op = smithy4sEndpoint.wrap(input)
+              impl(op)
+            }
+          case Some(errorSchema) =>
+            implicit val errorCodec: ErrorEncoder[E] = errorCodecFromSchema(errorSchema.schema)
+            Endpoint[F](methodName).apply[I, E, O] { (input: I) =>
+              val op = smithy4sEndpoint.wrap(input)
+              impl(op).attempt.flatMap {
+                case Left(err)      => errorResponse(err).map(r => Left(r): Either[E, O])
+                case Right(success) => (Right(success): Either[E, O]).pure
+              }
+            }
         }
     }
   }
+
+  private def errorCodecFromSchema[A](s: Schema[A]): ErrorEncoder[A] = { (a: A) =>
+    ErrorPayload(-32000, "JSONRPC-smithy4s application error", Some(Payload(CirceJson.fromSchema(s).apply(a))))
+  }
 }