If I have code that previously used the continuation style:

doA {
  doB {
    doC()
  }
}

And I want to make them all in the same level, would it be done like the following?

// Original
fun doA(continuation: () -> Unit) {
  // some action
  continuation()
}

// New
suspend fun doA() = suspendCoroutine<Unit> {
  // some action
  it.resume(Unit)
}

Then I do something like

launch {
  doA()
  doB()
  doC()
}

Which should occur one after the other by default. My goal is just to remove the nested brackets. The reason I have continuation to begin with is that the actions I’m running deal with callbacks. Is there also a benefit to doing some potential safety checks before calling suspendCoroutine vs putting them all inside that wrapper? The delay function seems to do that.

But I don't see any usage of callback here, why not just write your code sequentially, it's not clear for those examples why do you need callback and suspend

This is an example of an actual method I have:

private fun setWebCookie(cookie: String?, callback: (() -> Unit)?) {
    with(CookieManager.getInstance()) {
        removeAllCookies { _ ->
            if (cookie == null) {
                callback?.invoke()
                return@removeAllCookies
            }
            L.d { "Setting cookie" }
            val cookies = cookie.split(";").map { Pair(it, SingleSubject.create<Boolean>()) }
            cookies.forEach { (cookie, callback) -> setCookie(FB_URL_BASE, cookie) { callback.onSuccess(it) } }
            Observable.zip<Boolean, Unit>(cookies.map { (_, callback) -> callback.toObservable() }) {}
                    .observeOn(AndroidSchedulers.mainThread())
                    .subscribe {
                        callback?.invoke()
                        L.d { "Cookies set" }
                        L._d { cookie }
                        flush()
                    }
        }
    }
}

In android, remove all cookies and set cookies all take callbacks. I want to clear all cookies and then get set a bunch of cookies, before performing actions. All the other methods are similar.

I think you should replace the implementation of your

doA

,

doB

and

doC

with

suspend

function and remove the callback parameters

+1 to Dico, you just need suspend version of `removeAllCookies`/`setCookie`