pull common implementation of TracedHandler into shared TracedHandlerImpl

this allows for Scala version-specific interfaces but without
duplicating the implementation logic

Author: bpholt

lambda/shared/src/main/scala-2/feral/lambda/TracedHandlerPlatform.scala

@@ -18,28 +18,13 @@ package feral.lambda
 
 import cats.effect.{Trace => _, _}
 import cats.mtl.Local
-import cats.syntax.all._
 import natchez._
-import natchez.mtl._
 
 trait TracedHandlerPlatform {
   def apply[F[_]: MonadCancelThrow, Event, Result](entryPoint: EntryPoint[F])(
       handler: Trace[F] => F[Option[Result]])(
       implicit inv: Invocation[F, Event],
       KS: KernelSource[Event],
       L: Local[F, Span[F]]): F[Option[Result]] =
-    for {
-      event <- inv.event
-      context <- inv.context
-      kernel = KS.extract(event)
-      result <- entryPoint.continueOrElseRoot(context.functionName, kernel).use {
-        Local[F, Span[F]].scope {
-          Trace[F].put(
-            AwsTags.arn(context.invokedFunctionArn),
-            AwsTags.requestId(context.awsRequestId)
-          ) >> handler(Trace[F])
-        }
-      }
-    } yield result
-
+    TracedHandlerImpl[F, Event, Result](entryPoint)(handler)
 }

lambda/shared/src/main/scala-3/feral/lambda/TracedHandlerPlatform.scala

@@ -18,26 +18,12 @@ package feral.lambda
 
 import cats.effect.{Trace as _, *}
 import cats.mtl.Local
-import cats.syntax.all.*
 import natchez.*
-import natchez.mtl.*
 
 trait TracedHandlerPlatform:
   def apply[F[_]: MonadCancelThrow, Event, Result](entryPoint: EntryPoint[F])(
       handler: Trace[F] ?=> F[Option[Result]])(
       using Invocation[F, Event],
       KernelSource[Event],
       Local[F, Span[F]]): F[Option[Result]] =
-    for
-      event <- Invocation[F, Event].event
-      context <- Invocation[F, Event].context
-      kernel = KernelSource[Event].extract(event)
-      result <- entryPoint
-        .continueOrElseRoot(context.functionName, kernel)
-        .use:
-          Local[F, Span[F]].scope:
-            Trace[F].put(
-              AwsTags.arn(context.invokedFunctionArn),
-              AwsTags.requestId(context.awsRequestId)
-            ) >> handler
-    yield result
+    TracedHandlerImpl[F, Event, Result](entryPoint) { implicit t => handler }

lambda/shared/src/main/scala/feral/lambda/TracedHandler.scala

@@ -23,6 +23,7 @@ import cats.mtl.Local
 import cats.syntax.all._
 import fs2.compat.NotGiven
 import natchez._
+import natchez.mtl._
 
 object TracedHandler extends TracedHandlerPlatform {
 
@@ -81,3 +82,25 @@ object TracedHandler extends TracedHandlerPlatform {
   }
 
 }
+
+private[lambda] object TracedHandlerImpl {
+  def apply[F[_]: MonadCancelThrow, Event, Result](entryPoint: EntryPoint[F])(
+      handler: Trace[F] => F[Option[Result]])(
+      implicit inv: Invocation[F, Event],
+      KS: KernelSource[Event],
+      L: Local[F, Span[F]]): F[Option[Result]] =
+    for {
+      event <- Invocation[F, Event].event
+      context <- Invocation[F, Event].context
+      kernel = KernelSource[Event].extract(event)
+      result <- entryPoint.continueOrElseRoot(context.functionName, kernel).use {
+        Local[F, Span[F]].scope {
+          Trace[F].put(
+            AwsTags.arn(context.invokedFunctionArn),
+            AwsTags.requestId(context.awsRequestId)
+          ) >> handler(Trace[F])
+        }
+      }
+    } yield result
+
+}