func asyncF(_ item: Int, transform: (Int) async -> String)) async -> String { let out = await transform(item) print(out) return out } が、気持ち的にはこんな感じなんですよね↓ func asyncF(_ item: Int, transform: (Int) async -> String), nextContinuation: () -> Void) async { return transform(item, { out in print(out) return nextContinuation(out) }) } (edited)