Merge pull request #648 from alexcardell/add-mapk

Implement mapK syntax for EntryPoint and Span
typelevel · Nov 19, 2022 · bfa4e5c · bfa4e5c
2 parents 73bf08b + c2bcb52
commit bfa4e5c
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Showing 2 changed files with 57 additions and 3 deletions.
diff --git a/modules/core/shared/src/main/scala/EntryPoint.scala b/modules/core/shared/src/main/scala/EntryPoint.scala
@@ -4,6 +4,8 @@
 
 package natchez
 
+import cats.~>
+import cats.effect.MonadCancel
 import cats.effect.Resource
 
 /**
@@ -30,5 +32,31 @@ trait EntryPoint[F[_]] {
    */
   def continueOrElseRoot(name: String, kernel: Kernel): Resource[F, Span[F]]
 
-
+  /**
+    * Converts this `EntryPoint[F]` to an `EntryPoint[G]` using an `F ~> G`.
+    */
+  def mapK[G[_]](
+      f: F ~> G
+  )(implicit F: MonadCancel[F, _], G: MonadCancel[G, _]): EntryPoint[G] = {
+    val outer = this
+
+    def aux(r: Resource[F, Span[F]]): Resource[G, Span[G]] = r
+      .map(_.mapK(f))
+      .mapK(f)
+
+    new EntryPoint[G] {
+
+      override def root(name: String): Resource[G, Span[G]] = aux(outer.root(name))
+
+      override def continue(
+          name: String,
+          kernel: Kernel
+      ): Resource[G, Span[G]] = aux(outer.continue(name, kernel))
+
+      override def continueOrElseRoot(
+          name: String,
+          kernel: Kernel
+      ): Resource[G, Span[G]] = aux(outer.continueOrElseRoot(name, kernel))
+    }
+  }
 }
diff --git a/modules/core/shared/src/main/scala/Span.scala b/modules/core/shared/src/main/scala/Span.scala
@@ -4,11 +4,12 @@
 
 package natchez
 
-import cats.{~>, Applicative}
-import cats.syntax.applicative._
 import cats.data.Kleisli
+import cats.effect.MonadCancel
 import cats.effect.Resource
 import cats.effect.Resource.ExitCase
+import cats.syntax.applicative._
+import cats.{~>, Applicative}
 import java.net.URI
 
 /** An span that can be passed around and used to create child spans. */
@@ -44,6 +45,31 @@ trait Span[F[_]] {
    */
   def traceUri: F[Option[URI]]
 
+  /** Converts this `Span[F]` to a `Span[G]` using a `F ~> G`. */
+  def mapK[G[_]](f: F ~> G)(
+      implicit F: MonadCancel[F, _],
+      G: MonadCancel[G, _]
+  ): Span[G] = {
+    val outer = this
+    new Span[G] {
+      override def put(fields: (String, TraceValue)*): G[Unit] = f(
+        outer.put(fields: _*)
+      )
+
+      override def kernel: G[Kernel] = f(outer.kernel)
+
+      override def span(name: String): Resource[G, Span[G]] = outer
+        .span(name)
+        .map(_.mapK(f))
+        .mapK(f)
+
+      override def traceId: G[Option[String]] = f(outer.traceId)
+
+      override def spanId: G[Option[String]] = f(outer.spanId)
+
+      override def traceUri: G[Option[URI]] = f(outer.traceUri)
+    }
+  }
 }
 
 object Span {