Implement UUIDGen capability trait.

std/shared/src/main/scala/cats/effect/std/UUIDGen.scala

@@ -0,0 +1,45 @@
+/*
+ * Copyright 2020-2021 Typelevel
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package cats.effect.std
+
+import cats.Functor
+import cats.effect.kernel.Sync
+import cats.implicits._
+
+import java.util.UUID
+
+/**
+ * A purely functional UUID Generator
+ */
+trait UUIDGen[F[_]] {
+
+  /**
+   * Generates a UUID in a pseudorandom manner.
+   * @return randomly generated UUID
+   */
+  def randomUUID: F[UUID]
+}
+
+object UUIDGen {
+  def apply[F[_]](implicit ev: UUIDGen[F]): UUIDGen[F] = ev
+
+  implicit def fromSync[F[_]: Sync]: UUIDGen[F] = new UUIDGen[F] {
+    override def randomUUID: F[UUID] = Sync[F].delay(UUID.randomUUID())
+  }
+  def randomUUID[F[_]: UUIDGen]: F[UUID] = UUIDGen[F].randomUUID
+  def randomString[F[_]: UUIDGen: Functor]: F[String] = randomUUID.map(_.toString)
+}