@c
func callFromC() { ... }

// Generated C header
 
void callFromC(void);

@c(MyLibrary_callFromC)
func callFromC() { ... }

// Generated C header
 
void MyLibrary_callFromC(void);

// C header
 
void callFromC(void);

// Implementation written in Swift
 
@c @implementation
func callFromC() { ... }

import ModuleA
import ModuleB
 
let x = ModuleA::getValue() // Call 'getValue' from ModuleA
let y = ModuleB::getValue() // Call 'getValue' from ModuleB

let task = Swift::Task {
  // async work
}

```swift, nocopy
let config = loadDefaultConfig()
```

 ```swift, highlight=[1, 3]
let name = "World"       // highlighted
let greeting = "Hello"
print("\(greeting), \(name)!")  // highlighted
```

```swift, showLineNumbers, wrap=80
func example() { /* ... */ }
```

// In '-default-isolation MainActor' mode
 
struct Image {
  // The image cache is safe because it's protected
  // by the main actor.
  static var cachedImage: [URL: Image] = [:]
 
  static func create(from url: URL) async throws -> Image {
    if let image = cachedImage[url] {
      return image
    }
 
    let image = try await fetchImage(at: url)
 
    cachedImage[url] = image
    return image
  }
 
  // Fetch the data from the given URL and decode it.
  // This is performed on the concurrent thread pool to
  // keep the main actor free while decoding large images.
  @concurrent
  static func fetchImage(at url: URL) async throws -> Image {
    let (data, _) = try await URLSession.shared.data(from: url)
    return await decode(data: data)
  }
}

struct Game {
  // Shorthand for InlineArray<40, Sprite>
  var bricks: [40 of Sprite]
 
  init(_ brickSprite: Sprite) {
    bricks = .init(repeating: brickSprite)
  }
}

.target(
  name: "MyLibrary",
  swiftSettings: [
    .treatAllWarnings(as: .error),
    .treatWarning("DeprecatedDeclaration", as: .warning),
  ]
)

import Subprocess
 
let swiftPath = FilePath("/usr/bin/swift")
let result = try await run(
  .path(swiftPath),
  arguments: ["--version"]
)
 
let swiftVersion = result.standardOutput

  -@Test("square() returns x * x")
  -func squareIsXTimesX() {
  +@Test func `square() returns x * x`() {
     #expect(square(4) == 4 * 4)
   }