Refactor Allocator and syntax for improved clarity; update README to reflect changes

Author: igor-vovk

README.md

@@ -108,7 +108,7 @@ Allocator.create[IO]().withListener(new LoggingAllocationListener[IO])
 
 You can have multiple dependencies objects and combine them together. In this case, you can either reuse the same
 `Allocator` object or create a new one for each dependency object, but wrap their instantiation
-in `allocator.allocate { ... }` so that they are shut down in the right order:
+in `allocate { ... }` so that they are shut down in the right order:
 
 Example reusing the same `Allocator` object:
 
@@ -129,7 +129,7 @@ object Dependencies {
 }
 
 class Dependencies(using AllocatorIO) {
-  val aws = new AwsDependencies(allocator)
+  val aws = new AwsDependencies
 
   lazy val http4sClient: Client[IO] = allocate {
     EmberClientBuilder.default[IO].build
@@ -168,11 +168,11 @@ object Dependencies {
 }
 
 class Dependencies(using AllocatorIO) {
-  lazy val aws = allocator.allocate {
+  lazy val aws = allocate {
     AwsDependencies.create()
   }
 
-  lazy val http4sClient: Client[IO] = http4sAllocator.allocate {
+  lazy val http4sClient: Client[IO] = allocate {
     EmberClientBuilder.default[IO].build
   }
 }

src/main/scala/me/ivovk/cedi/Allocator.scala

@@ -15,8 +15,10 @@ object Allocator {
       dispatcher  <- Dispatcher.parallel[F]
       shutdownRef <- Ref.of(Async[F].unit).toResource
       allocator   <- {
-        val acquire = Async[F].delay(new Allocator(dispatcher, shutdownRef, NoOpListener[F]))
-        val release = (a: Allocator[F]) => a.shutdownAll
+        val acquire: F[Allocator[F]] = Async[F].delay {
+          new Allocator(dispatcher, shutdownRef, NoOpListener[F])
+        }
+        val release: Allocator[F] => F[Unit] = _.shutdownAll
 
         Resource.make(acquire)(release)
       }
@@ -56,7 +58,8 @@ class Allocator[F[_]: Sync] private (
     dispatcher.unsafeRunSync(fa)
   }
 
-  def allocate[A: ClassTag](fa: F[A]): A = allocate(fa.toResource)
+  def allocate[A: ClassTag](fa: F[A]): A =
+    allocate(fa.toResource)
 
   def shutdownAll: F[Unit] =
     shutdown.getAndSet(Sync[F].unit).flatten

src/main/scala/me/ivovk/cedi/syntax.scala

@@ -7,7 +7,8 @@ import scala.reflect.ClassTag
 object syntax {
 
   type Allocator[F[_]] = me.ivovk.cedi.Allocator[F]
-  type AllocatorIO     = me.ivovk.cedi.Allocator[IO]
+  val Allocator: me.ivovk.cedi.Allocator.type = me.ivovk.cedi.Allocator
+  type AllocatorIO = me.ivovk.cedi.Allocator[IO]
 
   def allocate[F[_]: Allocator, A: ClassTag](fa: F[A]): A =
     Allocator[F].allocate(fa)