setup a swift package that is an executable.

This is done by removing products from the package.swift file, set a platform to macOS, replace tartet with .executable.
Add a main.swift file inside the sources folder.

Author: tobitech

Diff for: Package.swift

@@ -4,25 +4,16 @@
 import PackageDescription
 
 let package = Package(
-    name: "concurrency",
-    products: [
-        // Products define the executables and libraries a package produces, and make them visible to other packages.
-        .library(
-            name: "concurrency",
-            targets: ["concurrency"]),
-    ],
-    dependencies: [
-        // Dependencies declare other packages that this package depends on.
-        // .package(url: /* package url */, from: "1.0.0"),
-    ],
-    targets: [
-        // Targets are the basic building blocks of a package. A target can define a module or a test suite.
-        // Targets can depend on other targets in this package, and on products in packages this package depends on.
-        .target(
-            name: "concurrency",
-            dependencies: []),
-        .testTarget(
-            name: "concurrencyTests",
-            dependencies: ["concurrency"]),
-    ]
+  name: "concurrency",
+  platforms: [.macOS(.v12)],
+  dependencies: [],
+  targets: [
+    .executableTarget(
+      name: "concurrency",
+      dependencies: []
+    ),
+    .testTarget(
+      name: "concurrencyTests",
+      dependencies: ["concurrency"]),
+  ]
 )

Diff for: Sources/concurrency/concurrency.swift

@@ -0,0 +1 @@
+