Merge pull request #4220 from bio-aeon/add-uuidgen-optiont-materializer

Add `UUIDGen` inductive materializers for monad transformers
typelevel · Jan 2, 2025 · a49a028 · a49a028
2 parents 0cb794b + 6495734
commit a49a028
Showing 1 changed file with 88 additions and 3 deletions.
diff --git a/std/shared/src/main/scala/cats/effect/std/UUIDGen.scala b/std/shared/src/main/scala/cats/effect/std/UUIDGen.scala
@@ -16,29 +16,107 @@
 
 package cats.effect.std
 
-import cats.Functor
+import cats.{~>, Applicative, Functor, Monoid}
+import cats.data.{
+  EitherT,
+  IndexedReaderWriterStateT,
+  IndexedStateT,
+  IorT,
+  Kleisli,
+  OptionT,
+  WriterT
+}
 import cats.implicits._
 
 import java.util.UUID
 
 /**
  * A purely functional UUID Generator
  */
-trait UUIDGen[F[_]] {
+trait UUIDGen[F[_]] { self =>
 
   /**
    * Generates a UUID in a pseudorandom manner.
    * @return
    *   randomly generated UUID
    */
   def randomUUID: F[UUID]
+
+  /**
+   * Modifies the context in which this [[UUIDGen]] operates using the natural transformation
+   * `f`.
+   *
+   * @return
+   *   a [[UUIDGen]] in the new context obtained by mapping the current one using `f`
+   */
+  def mapK[G[_]](f: F ~> G): UUIDGen[G] =
+    new UUIDGen.TranslatedUUIDGen[F, G](self)(f)
 }
 
 object UUIDGen extends UUIDGenCompanionPlatform {
   def apply[F[_]](implicit ev: UUIDGen[F]): UUIDGen[F] = ev
 
   def randomUUID[F[_]: UUIDGen]: F[UUID] = UUIDGen[F].randomUUID
-  def randomString[F[_]: UUIDGen: Functor]: F[String] = randomUUID.map(_.toString)
+  def randomString[F[_]](implicit gen: UUIDGen[F], F: Functor[F]): F[String] =
+    randomUUID(gen).map(_.toString)
+
+  /**
+   * [[UUIDGen]] instance built for `cats.data.EitherT` values initialized with any `F` data
+   * type that also implements `UUIDGen`.
+   */
+  implicit def catsEitherTUUIDGen[F[_]: UUIDGen: Functor, L]: UUIDGen[EitherT[F, L, *]] =
+    UUIDGen[F].mapK(EitherT.liftK)
+
+  /**
+   * [[UUIDGen]] instance built for `cats.data.Kleisli` values initialized with any `F` data
+   * type that also implements `UUIDGen`.
+   */
+  implicit def catsKleisliUUIDGen[F[_]: UUIDGen, R]: UUIDGen[Kleisli[F, R, *]] =
+    UUIDGen[F].mapK(Kleisli.liftK)
+
+  /**
+   * [[UUIDGen]] instance built for `cats.data.OptionT` values initialized with any `F` data
+   * type that also implements `UUIDGen`.
+   */
+  implicit def catsOptionTUUIDGen[F[_]: UUIDGen: Functor]: UUIDGen[OptionT[F, *]] =
+    UUIDGen[F].mapK(OptionT.liftK)
+
+  /**
+   * [[UUIDGen]] instance built for `cats.data.IndexedStateT` values initialized with any `F`
+   * data type that also implements `UUIDGen`.
+   */
+  implicit def catsIndexedStateTUUIDGen[F[_]: UUIDGen: Applicative, S]
+      : UUIDGen[IndexedStateT[F, S, S, *]] =
+    UUIDGen[F].mapK(IndexedStateT.liftK)
+
+  /**
+   * [[UUIDGen]] instance built for `cats.data.WriterT` values initialized with any `F` data
+   * type that also implements `UUIDGen`.
+   */
+  implicit def catsWriterTUUIDGen[
+      F[_]: UUIDGen: Applicative,
+      L: Monoid
+  ]: UUIDGen[WriterT[F, L, *]] =
+    UUIDGen[F].mapK(WriterT.liftK)
+
+  /**
+   * [[UUIDGen]] instance built for `cats.data.IorT` values initialized with any `F` data type
+   * that also implements `UUIDGen`.
+   */
+  implicit def catsIorTUUIDGen[F[_]: UUIDGen: Functor, L]: UUIDGen[IorT[F, L, *]] =
+    UUIDGen[F].mapK(IorT.liftK)
+
+  /**
+   * [[UUIDGen]] instance built for `cats.data.IndexedReaderWriterStateT` values initialized
+   * with any `F` data type that also implements `UUIDGen`.
+   */
+  implicit def catsIndexedReaderWriterStateTUUIDGen[
+      F[_]: UUIDGen: Applicative,
+      E,
+      L: Monoid,
+      S
+  ]: UUIDGen[IndexedReaderWriterStateT[F, E, L, S, S, *]] =
+    UUIDGen[F].mapK(IndexedReaderWriterStateT.liftK)
 
   implicit def fromSecureRandom[F[_]: Functor: SecureRandom]: UUIDGen[F] =
     new UUIDGen[F] {
@@ -59,4 +137,11 @@ object UUIDGen extends UUIDGenCompanionPlatform {
         new UUID(msb, lsb)
       }
     }
+
+  private[std] final class TranslatedUUIDGen[F[_], G[_]](self: UUIDGen[F])(f: F ~> G)
+      extends UUIDGen[G] {
+    override def randomUUID: G[UUID] =
+      f(self.randomUUID)
+
+  }
 }