pointfreeco · stephencelis · Jul 3, 2026
diff --git a/Package.swift b/Package.swift
@@ -34,7 +34,6 @@ let package = Package(
   dependencies: [
     .package(url: "https://github.com/pointfreeco/combine-schedulers", from: "1.0.0"),
     .package(url: "https://github.com/pointfreeco/swift-case-paths", from: "1.7.3"),
-    .package(url: "https://github.com/pointfreeco/swift-concurrency-extras", from: "1.3.0"),
     .package(url: "https://github.com/pointfreeco/swift-custom-dump", from: "1.0.0"),
     .package(url: "https://github.com/pointfreeco/swift-dependencies", from: "1.5.1"),
     .package(url: "https://github.com/pointfreeco/swift-identified-collections", from: "1.0.0"),
@@ -55,7 +54,6 @@ let package = Package(
             traits: ["CasePaths"]
           )
         ),
-        .product(name: "ConcurrencyExtras", package: "swift-concurrency-extras"),
         .product(
           name: "CustomDump",
           package: "swift-custom-dump",

diff --git a/Package@swift-5.9.swift b/Package@swift-5.9.swift
@@ -17,7 +17,6 @@ let package = Package(
     )
   ],
   dependencies: [
-    .package(url: "https://github.com/pointfreeco/swift-concurrency-extras", from: "1.3.0"),
     .package(url: "https://github.com/pointfreeco/swift-custom-dump", from: "1.0.0"),
     .package(url: "https://github.com/pointfreeco/swift-dependencies", from: "1.5.1"),
     .package(url: "https://github.com/pointfreeco/swift-identified-collections", from: "1.0.0"),
@@ -31,7 +30,6 @@ let package = Package(
       dependencies: [
         "Sharing1",
         "Sharing2",
-        .product(name: "ConcurrencyExtras", package: "swift-concurrency-extras"),
         .product(name: "CustomDump", package: "swift-custom-dump"),
         .product(name: "Dependencies", package: "swift-dependencies"),
         .product(name: "IdentifiedCollections", package: "swift-identified-collections"),

diff --git a/Package@swift-6.0.swift b/Package@swift-6.0.swift
@@ -18,7 +18,6 @@ let package = Package(
   ],
   dependencies: [
     .package(url: "https://github.com/pointfreeco/combine-schedulers", from: "1.0.0"),
-    .package(url: "https://github.com/pointfreeco/swift-concurrency-extras", from: "1.3.0"),
     .package(url: "https://github.com/pointfreeco/swift-custom-dump", from: "1.0.0"),
     .package(url: "https://github.com/pointfreeco/swift-dependencies", from: "1.5.1"),
     .package(url: "https://github.com/pointfreeco/swift-identified-collections", from: "1.0.0"),
@@ -32,7 +31,6 @@ let package = Package(
       dependencies: [
         "Sharing1",
         "Sharing2",
-        .product(name: "ConcurrencyExtras", package: "swift-concurrency-extras"),
         .product(name: "CustomDump", package: "swift-custom-dump"),
         .product(name: "Dependencies", package: "swift-dependencies"),
         .product(name: "IdentifiedCollections", package: "swift-identified-collections"),

diff --git a/Sources/Sharing/Internal/LockIsolated.swift b/Sources/Sharing/Internal/LockIsolated.swift
@@ -0,0 +1,16 @@
+import class Foundation.NSLock
+
+package final class LockIsolated<Value>: @unchecked Sendable {
+  private var value: Value
+  private let lock = NSLock()
+  package init(_ value: sending Value) {
+    self.value = value
+  }
+  package func withLock<R, F: Error>(
+    _ operation: (inout sending Value) throws(F) -> sending R
+  ) throws(F) -> sending R {
+    lock.lock()
+    defer { lock.unlock() }
+    return try operation(&value)
+  }
+}
diff --git a/Sources/Sharing/SharedKeys/AppStorageKey.swift b/Sources/Sharing/SharedKeys/AppStorageKey.swift
@@ -1,5 +1,4 @@
 #if canImport(AppKit) || canImport(UIKit) || canImport(WatchKit)
-  import ConcurrencyExtras
   public import Dependencies
   @preconcurrency public import Foundation
   import IssueReporting

diff --git a/Sources/Sharing/SharedKeys/FileStorageKey.swift b/Sources/Sharing/SharedKeys/FileStorageKey.swift
@@ -1,6 +1,5 @@
 #if canImport(AppKit) || canImport(UIKit) || canImport(WatchKit)
   import Combine
-  public import ConcurrencyExtras
   public import Dependencies
   @preconcurrency import Dispatch
 
@@ -143,7 +142,7 @@
                   setUpSources()
                 }
               }
-              if state.withValue({ $0.workItem == nil }) {
+              if state.withLock({ $0.workItem == nil }) {
                 if fileExists {
                   subscriber.yield(with: Result { try self.decode(self.storage.load(self.url)) })
                 } else {
@@ -161,7 +160,7 @@
                 ? (try? self.storage.attributesOfItemAtPath(self.url.path)[.modificationDate]
                   as? Date)
                 : nil
-              let shouldYield = state.withValue { state in
+              let shouldYield = state.withLock { state in
                 guard fileExists
                 else {
                   state.cancelWorkItem()
@@ -210,7 +209,7 @@
 
     public func save(_ value: Value, context: SaveContext, continuation: SaveContinuation) {
       do {
-        let workItem: DispatchWorkItem? = try state.withValue { state in
+        let workItem: DispatchWorkItem? = try state.withLock { state in
           let data = try encode(value)
           switch context {
           case .didSet:
@@ -224,7 +223,7 @@
             continuation.resume()
             let workItem = DispatchWorkItem { [weak self] in
               guard let self else { return }
-              self.state.withValue { state in
+              self.state.withLock { state in
                 defer {
                   state.value = nil
                   state.workItem = nil
@@ -334,7 +333,7 @@
       @Sendable (URL, DispatchSource.FileSystemEvent, @escaping @Sendable () -> Void) throws ->
         SharedSubscription
     let load: @Sendable (URL) throws -> Data
-    @_spi(Internals) public let save: @Sendable (Data, URL) throws -> Void
+    public let save: @Sendable (Data, URL) throws -> Void
 
     /// File storage that interacts directly with the file system for saving, loading and listening
     /// for file changes.
@@ -391,7 +390,7 @@
       inMemory(fileSystem: LockIsolated([:]))
     }
 
-    @_spi(Internals) public static func inMemory(
+    package static func inMemory(
       fileSystem: LockIsolated<[URL: Data]>,
       async: @escaping @Sendable (DispatchWorkItem) -> Void = { $0.perform() },
       asyncAfter: @escaping @Sendable (DispatchTimeInterval, DispatchWorkItem) -> Void = {
@@ -405,22 +404,22 @@
         asyncAfter: asyncAfter,
         attributesOfItemAtPath: { _ in [:] },
         createDirectory: { _, _ in },
-        fileExists: { fileSystem.keys.contains($0) },
+        fileExists: { url in fileSystem.withLock { $0.keys.contains(url) } },
         fileSystemSource: { url, event, handler in
           guard event.contains(.write)
           else { return SharedSubscription {} }
           return SharedSubscription {}
         },
         load: {
-          guard let data = fileSystem[$0]
+          guard let data = fileSystem.withLock(\.[$0])
           else {
             struct LoadError: Error {}
             throw LoadError()
           }
           return data
         },
         save: { data, url in
-          fileSystem.withValue { $0[url] = data }
+          fileSystem.withLock { $0[url] = data }
         }
       )
     }

diff --git a/Tests/SharingTests/FileStorageTests.swift b/Tests/SharingTests/FileStorageTests.swift
@@ -1,16 +1,15 @@
 #if canImport(AppKit) || canImport(UIKit) || canImport(WatchKit)
   import Combine
   import CombineSchedulers
-  import ConcurrencyExtras
   import CustomDump
   import Dependencies
   import DependenciesTestSupport
   import Foundation
-  @_spi(Internals) import Sharing
+  import Sharing
   import Testing
 
   @Suite struct FileStorageTests {
-    let fileSystem = LockIsolated<[URL: Data]>([:])
+    let fileSystem = Sharing.LockIsolated<[URL: Data]>([:])
     let testScheduler = DispatchQueue.test
 
     @Test func basics() throws {
@@ -20,11 +19,11 @@
         @Shared(.fileStorage(.fileURL)) var users = [User]()
         #expect($users.loadError == nil)
         expectNoDifference(
-          fileSystem.value,
+          fileSystem.withLock(\.self),
           [.fileURL: Data()]
         )
         $users.withLock { $0.append(.blob) }
-        try expectNoDifference(fileSystem.value.users(for: .fileURL), [.blob])
+        try expectNoDifference(fileSystem.withLock(\.self).users(for: .fileURL), [.blob])
       }
     }
 
@@ -35,12 +34,12 @@
         @Shared(.utf8String) var string = ""
         #expect($string.loadError == nil)
         expectNoDifference(
-          fileSystem.value,
+          fileSystem.withLock(\.self),
           [.utf8StringURL: Data()]
         )
         $string.withLock { $0 = "hello" }
         expectNoDifference(
-          fileSystem.value[.utf8StringURL].map { String(decoding: $0, as: UTF8.self) },
+          fileSystem.withLock(\.self)[.utf8StringURL].map { String(decoding: $0, as: UTF8.self) },
           "hello"
         )
       }
@@ -51,26 +50,26 @@
         $0.defaultFileStorage = .inMemory(fileSystem: fileSystem, scheduler: testScheduler)
       } operation: {
         @Shared(.fileStorage(.fileURL)) var users = [User]()
-        try expectNoDifference(fileSystem.value.users(for: .fileURL), nil)
+        try expectNoDifference(fileSystem.withLock(\.self).users(for: .fileURL), nil)
 
         $users.withLock { $0.append(.blob) }
-        try expectNoDifference(fileSystem.value.users(for: .fileURL), [.blob])
+        try expectNoDifference(fileSystem.withLock(\.self).users(for: .fileURL), [.blob])
 
         $users.withLock { $0.append(.blobJr) }
         testScheduler.advance(by: .seconds(1) - .milliseconds(1))
-        try expectNoDifference(fileSystem.value.users(for: .fileURL), [.blob])
+        try expectNoDifference(fileSystem.withLock(\.self).users(for: .fileURL), [.blob])
 
         $users.withLock { $0.append(.blobSr) }
         testScheduler.advance(by: .milliseconds(1))
-        try expectNoDifference(fileSystem.value.users(for: .fileURL), [.blob, .blobJr, .blobSr])
+        try expectNoDifference(fileSystem.withLock(\.self).users(for: .fileURL), [.blob, .blobJr, .blobSr])
 
         testScheduler.advance(by: .seconds(1))
-        try expectNoDifference(fileSystem.value.users(for: .fileURL), [.blob, .blobJr, .blobSr])
+        try expectNoDifference(fileSystem.withLock(\.self).users(for: .fileURL), [.blob, .blobJr, .blobSr])
 
         testScheduler.advance(by: .seconds(0.5))
         $users.withLock { $0.append(.blobEsq) }
         try expectNoDifference(
-          fileSystem.value.users(for: .fileURL),
+          fileSystem.withLock(\.self).users(for: .fileURL),
           [
             .blob,
             .blobJr,
@@ -86,14 +85,14 @@
         $0.defaultFileStorage = .inMemory(fileSystem: fileSystem, scheduler: testScheduler)
       } operation: {
         @Shared(.fileStorage(.fileURL)) var users = [User]()
-        try expectNoDifference(fileSystem.value.users(for: .fileURL), nil)
+        try expectNoDifference(fileSystem.withLock(\.self).users(for: .fileURL), nil)
 
         $users.withLock { $0.append(.blob) }
-        try expectNoDifference(fileSystem.value.users(for: .fileURL), [.blob])
+        try expectNoDifference(fileSystem.withLock(\.self).users(for: .fileURL), [.blob])
 
         testScheduler.advance(by: .seconds(2))
         $users.withLock { $0.append(.blobJr) }
-        try expectNoDifference(fileSystem.value.users(for: .fileURL), [.blob, .blobJr])
+        try expectNoDifference(fileSystem.withLock(\.self).users(for: .fileURL), [.blob, .blobJr])
       }
     }
 
@@ -114,17 +113,17 @@
         @Shared(.fileStorage(.anotherFileURL)) var otherUsers = [User]()
 
         $users.withLock { $0.append(.blob) }
-        try expectNoDifference(fileSystem.value.users(for: .fileURL), [.blob])
-        try expectNoDifference(fileSystem.value.users(for: .anotherFileURL), nil)
+        try expectNoDifference(fileSystem.withLock(\.self).users(for: .fileURL), [.blob])
+        try expectNoDifference(fileSystem.withLock(\.self).users(for: .anotherFileURL), nil)
 
         $otherUsers.withLock { $0.append(.blobJr) }
-        try expectNoDifference(fileSystem.value.users(for: .fileURL), [.blob])
-        try expectNoDifference(fileSystem.value.users(for: .anotherFileURL), [.blobJr])
+        try expectNoDifference(fileSystem.withLock(\.self).users(for: .fileURL), [.blob])
+        try expectNoDifference(fileSystem.withLock(\.self).users(for: .anotherFileURL), [.blobJr])
       }
     }
 
     @Test func initialValue() async throws {
-      let fileSystem = try LockIsolated<[URL: Data]>(
+      let fileSystem = Sharing.LockIsolated<[URL: Data]>(
         [.fileURL: try JSONEncoder().encode([User.blob])]
       )
       try await withDependencies {
@@ -133,12 +132,12 @@
         @Shared(.fileStorage(.fileURL)) var users = [User]()
         _ = users
         await Task.yield()
-        try expectNoDifference(fileSystem.value.users(for: .fileURL), [.blob])
+        try expectNoDifference(fileSystem.withLock(\.self).users(for: .fileURL), [.blob])
       }
     }
 
     @Test func decodeFailure() async throws {
-      let fileSystem = LockIsolated<[URL: Data]>(
+      let fileSystem = Sharing.LockIsolated<[URL: Data]>(
         [.fileURL: Data("corrupt".utf8)]
       )
       try withDependencies {
@@ -488,7 +487,7 @@
 
   extension FileStorage {
     fileprivate static func inMemory<S: Scheduler & Sendable>(
-      fileSystem: LockIsolated<[URL: Data]>,
+      fileSystem: Sharing.LockIsolated<[URL: Data]>,
       scheduler: S
     ) -> Self where S.SchedulerTimeType == DispatchQueue.SchedulerTimeType {
       .inMemory(