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0194-concurrency-pt5/README.md

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+## [Point-Free](https://www.pointfree.co)
+
+> #### This directory contains code from Point-Free Episode: [Concurrency's Future: Structured and Unstructured](https://www.pointfree.co/episodes/ep194-concurrency-s-future-structured-and-unstructured)
+>
+> There are amazing features of Swift concurrency that don’t quite fit into our narrative of examining it through the lens of past concurrency tools. Instead, we’ll examine them through the lens of a past programming paradigm, structured programming, and see what is has to say about structured concurrency.

0194-concurrency-pt5/concurrency/.gitignore

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+.DS_Store
+/.build
+/Packages
+/*.xcodeproj
+xcuserdata/
+DerivedData/
+.swiftpm/config/registries.json
+.swiftpm/xcode/package.xcworkspace/contents.xcworkspacedata
+.netrc

0194-concurrency-pt5/concurrency/.swiftpm/xcode/xcshareddata/xcschemes/concurrency.xcscheme

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+<?xml version="1.0" encoding="UTF-8"?>
+<Scheme
+   LastUpgradeVersion = "1340"
+   version = "1.3">
+   <BuildAction
+      parallelizeBuildables = "YES"
+      buildImplicitDependencies = "YES">
+      <BuildActionEntries>
+         <BuildActionEntry
+            buildForTesting = "YES"
+            buildForRunning = "YES"
+            buildForProfiling = "YES"
+            buildForArchiving = "YES"
+            buildForAnalyzing = "YES">
+            <BuildableReference
+               BuildableIdentifier = "primary"
+               BlueprintIdentifier = "concurrency"
+               BuildableName = "concurrency"
+               BlueprintName = "concurrency"
+               ReferencedContainer = "container:">
+            </BuildableReference>
+         </BuildActionEntry>
+         <BuildActionEntry
+            buildForTesting = "YES"
+            buildForRunning = "YES"
+            buildForProfiling = "NO"
+            buildForArchiving = "NO"
+            buildForAnalyzing = "YES">
+            <BuildableReference
+               BuildableIdentifier = "primary"
+               BlueprintIdentifier = "concurrencyTests"
+               BuildableName = "concurrencyTests"
+               BlueprintName = "concurrencyTests"
+               ReferencedContainer = "container:">
+            </BuildableReference>
+         </BuildActionEntry>
+      </BuildActionEntries>
+   </BuildAction>
+   <TestAction
+      buildConfiguration = "Debug"
+      selectedDebuggerIdentifier = "Xcode.DebuggerFoundation.Debugger.LLDB"
+      selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
+      shouldUseLaunchSchemeArgsEnv = "YES">
+      <Testables>
+         <TestableReference
+            skipped = "NO">
+            <BuildableReference
+               BuildableIdentifier = "primary"
+               BlueprintIdentifier = "concurrencyTests"
+               BuildableName = "concurrencyTests"
+               BlueprintName = "concurrencyTests"
+               ReferencedContainer = "container:">
+            </BuildableReference>
+         </TestableReference>
+      </Testables>
+   </TestAction>
+   <LaunchAction
+      buildConfiguration = "Release"
+      selectedDebuggerIdentifier = "Xcode.DebuggerFoundation.Debugger.LLDB"
+      selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
+      launchStyle = "0"
+      useCustomWorkingDirectory = "NO"
+      ignoresPersistentStateOnLaunch = "NO"
+      debugDocumentVersioning = "YES"
+      debugServiceExtension = "internal"
+      allowLocationSimulation = "YES">
+      <BuildableProductRunnable
+         runnableDebuggingMode = "0">
+         <BuildableReference
+            BuildableIdentifier = "primary"
+            BlueprintIdentifier = "concurrency"
+            BuildableName = "concurrency"
+            BlueprintName = "concurrency"
+            ReferencedContainer = "container:">
+         </BuildableReference>
+      </BuildableProductRunnable>
+   </LaunchAction>
+   <ProfileAction
+      buildConfiguration = "Release"
+      shouldUseLaunchSchemeArgsEnv = "YES"
+      savedToolIdentifier = ""
+      useCustomWorkingDirectory = "NO"
+      debugDocumentVersioning = "YES">
+      <BuildableProductRunnable
+         runnableDebuggingMode = "0">
+         <BuildableReference
+            BuildableIdentifier = "primary"
+            BlueprintIdentifier = "concurrency"
+            BuildableName = "concurrency"
+            BlueprintName = "concurrency"
+            ReferencedContainer = "container:">
+         </BuildableReference>
+      </BuildableProductRunnable>
+   </ProfileAction>
+   <AnalyzeAction
+      buildConfiguration = "Debug">
+   </AnalyzeAction>
+   <ArchiveAction
+      buildConfiguration = "Release"
+      revealArchiveInOrganizer = "YES">
+   </ArchiveAction>
+</Scheme>

0194-concurrency-pt5/concurrency/Package.swift

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+// swift-tools-version: 5.6
+// The swift-tools-version declares the minimum version of Swift required to build this package.
+
+import PackageDescription
+
+let package = Package(
+  name: "concurrency",
+  platforms: [.macOS(.v12)],
+  dependencies: [
+  ],
+  targets: [
+    .executableTarget(
+      name: "concurrency",
+      dependencies: [],
+      swiftSettings: [
+        .unsafeFlags([
+          "-Xfrontend", "-warn-concurrency",
+        ]),
+      ]
+    ),
+    .testTarget(
+      name: "concurrencyTests",
+      dependencies: ["concurrency"]),
+  ]
+)

0194-concurrency-pt5/concurrency/README.md

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+# concurrency
+
+A description of this package.

0194-concurrency-pt5/concurrency/Sources/concurrency/Combine.swift

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+import Combine
+import Foundation
+
+let publisher1 = Deferred {
+  Future<Int, Never> { callback in
+    print(Thread.current)
+    callback(.success(42))
+  }
+}
+  .subscribe(on: DispatchQueue(label: "queue1"))
+
+let publisher2 = Deferred {
+  Future<String, Never> { callback in
+    print(Thread.current)
+    callback(.success("Hello world"))
+  }
+}
+  .subscribe(on: DispatchQueue(label: "queue2"))
+
+let cancellable = publisher1
+  .flatMap { integer in
+    Deferred {
+      Future<String, Never> { callback in
+        print(Thread.current)
+        callback(.success("\(integer)"))
+      }
+    }
+    .subscribe(on: DispatchQueue(label: "queue3"))
+  }
+  .zip(publisher2)
+  .sink {
+  print("sink", $0, Thread.current)
+}
+
+//_ = cancellable
+
+
+func operationQueueCoordination() {
+  let queue = OperationQueue()
+
+  let operationA = BlockOperation {
+    print("A")
+    Thread.sleep(forTimeInterval: 1)
+  }
+  let operationB = BlockOperation {
+    print("B")
+  }
+  let operationC = BlockOperation {
+    print("C")
+  }
+  let operationD = BlockOperation {
+    print("D")
+  }
+  operationB.addDependency(operationA)
+  operationC.addDependency(operationA)
+  operationD.addDependency(operationB)
+  operationD.addDependency(operationC)
+  queue.addOperation(operationA)
+  queue.addOperation(operationB)
+  queue.addOperation(operationC)
+  queue.addOperation(operationD)
+
+  operationA.cancel()
+
+  /*
+    A ➡️ B
+   ⬇️    ⬇️
+    C ➡️ D
+   */
+}
+
+//a
+//  .handleEvents(...)
+//  .compactMap { $0 }
+//  .flatMap { a in zip(b(a), c(a)) }
+//  .flatMap { b, c in d(b, c) }
+//  .handleEvents(receiveCompletion: { _ in print("Finished") })
+
+// defer { print("Finished") }
+// guard let a = await f()
+// else { return }
+// async let b = g(a)
+// async let c = h(a)
+// let d = await i(b, c)
+
+
+func dispatchDiamondDependency() {
+  let queue = DispatchQueue(label: "queue", attributes: .concurrent)
+  queue.async {
+    print("A")
+
+    let group = DispatchGroup()
+    queue.async(group: group) {
+      print("B")
+    }
+    queue.async(group: group) {
+      print("C")
+    }
+
+    group.notify(queue: queue) {
+      print("D")
+    }
+  }
+}