Async defer

async-defer.swift

@discardableResult
func run<T>(_ operation: () async throws -> T,
            defer deferredOperation: () async throws -> Void) async throws -> T {
    do {
        let result = try await operation()
        try await deferredOperation()
        return result
    } catch {
        try await deferredOperation()
        throw error
    }
}

// Usage:

try await run {
    print("doing")
    try await Task.sleep(for: .seconds(1))
    print("done")
} defer: {
    try await Task.sleep(for: .milliseconds(100))
    print("cleanup done")
}