fixes #1180: Type-class instances for zio.Config (#1406)

core/shared/src/main/scala/zio/prelude/Associative.scala

@@ -17,7 +17,7 @@
 package zio.prelude
 
 import zio.prelude.newtypes.{And, AndF, AndThen, Both, First, Last, Max, Min, Natural, Or, OrF, Prod, Sum}
-import zio.{Cause, Chunk, Duration => ZIODuration, NonEmptyChunk}
+import zio.{Cause, Chunk, ConfigProvider, Duration => ZIODuration, NonEmptyChunk}
 
 import scala.annotation.tailrec
 
@@ -352,6 +352,12 @@ object Associative extends AssociativeLowPriority {
   implicit def ChunkIdentity[A]: Identity[Chunk[A]] =
     Identity.make(Chunk.empty, _ ++ _)
 
+  /**
+   * The `Associative` instance for `ConfigProvider`.
+   */
+  implicit val ConfigProviderAssociative: Associative[ConfigProvider] =
+    Associative.make(_.orElse(_))
+
   /**
    * Derives an `Associative[F[A]]` given a `Derive[F, Associative]` and an
    * `Associative[A]`.

core/shared/src/main/scala/zio/prelude/AssociativeBoth.scala

@@ -1074,6 +1074,15 @@ object AssociativeBoth extends AssociativeBothLowPriority {
       def both[A, B](fa: => Chunk[A], fb: => Chunk[B]): Chunk[(A, B)] = fa.flatMap(a => fb.map(b => (a, b)))
     }
 
+  /**
+   * The `IdentityBoth` instance for `Config`.
+   */
+  implicit val ConfigIdentityBoth: IdentityBoth[Config] =
+    new IdentityBoth[Config] {
+      val any: Config[Any]                                               = Config.succeed(())
+      def both[A, B](fa: => Config[A], fb: => Config[B]): Config[(A, B)] = fa ++ fb
+    }
+
   /**
    * The `AssociativeBoth` instance for `Const`.
    */

core/shared/src/main/scala/zio/prelude/AssociativeEither.scala

@@ -57,6 +57,15 @@ object AssociativeEither {
         Chunk.empty
     }
 
+  /**
+   * The `AssociativeEither` instance for `Config`.
+   */
+  implicit val ConfigAssociativeEither: AssociativeEither[Config] =
+    new AssociativeEither[Config] {
+      def either[A, B](fa: => Config[A], fb: => Config[B]): Config[Either[A, B]] =
+        fa.map(Left(_)).orElse(fb.map(Right(_)))
+    }
+
   /**
    * The `AssociativeEither` instance for `Either`.
    */

core/shared/src/main/scala/zio/prelude/Invariant.scala

@@ -16,11 +16,11 @@
 
 package zio.prelude
 
+import zio._
 import zio.prelude.coherent.CovariantIdentityBoth
 import zio.prelude.newtypes.Failure
 import zio.stm.ZSTM
 import zio.stream.{ZSink, ZStream}
-import zio.{Cause, Chunk, ChunkBuilder, Exit, Fiber, NonEmptyChunk, Schedule, ZIO}
 
 import scala.concurrent.{ExecutionContext, Future}
 import scala.util.Try
@@ -98,6 +98,16 @@ object Invariant extends LowPriorityInvariantImplicits with InvariantVersionSpec
         )
     }
 
+  /**
+   * The `Covariant` instance for `Config`.
+   */
+  implicit def ConfigCovariant[A]: Covariant[Config] =
+    new Covariant[Config] {
+      override def map[A, B](f: A => B): Config[A] => Config[B] = { config =>
+        config.map(f)
+      }
+    }
+
   /**
    * The `ForEach` instance for `Const`.
    */