AsyncSequence.eraseToAsyncStream()

AsyncSequenceExtensions.swift

import Foundation

// Props to @pteasima and @MichalKleinJr:
// https://twitter.com/pteasima/status/1544723987606929408?s=21&t=JL1oIuL87Ms_VPBQBZQ7Rg
public extension AsyncSequence {
    func eraseToAsyncStream() -> AsyncStream<Element> {
        return AsyncStream { continuation in
            let task = Task {
                do {
                    for try await value in self {
                        try Task.checkCancellation()
                        continuation.yield(value)
                    }
                    continuation.finish()
                } catch {
                    continuation.finish()
                }
            }
            continuation.onTermination = { _ in task.cancel() }
        }
    }
    
    func eraseToAsyncThrowingStream() -> AsyncThrowingStream<Element, Error> {
        return AsyncThrowingStream { continuation in
            let task = Task {
                do {
                    for try await value in self {
                        try Task.checkCancellation()
                        continuation.yield(value)
                    }
                    continuation.finish()
                } catch {
                    continuation.finish(throwing: error)
                }
            }
            continuation.onTermination = { _ in task.cancel() }
        }
    }
}