Comment by maxtaco | Hacker News Reader

Comment by maxtaco | Hacker News Reader

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My first thought for implementing tame.js was with yield, but V8 doesn't currently support it (though it's reserved as a "future" keyword). A direct use of yield (without anything like twait) would probably make node code look more like Python/Twisted code, which while better than the status quo, still can get unmanageable in my experience.

Agreed that twait conflates concurrency with blocking/callbacks, but it my experience, it's a natural and useful combination.

I think you could do something manageable with yield alone (at least with python-style generators). I've been meaning to try something like this with tornado. The general idea is that yielding would either immediately produce a callback or asynchronously "wait" for a previously-generated callback to be run. It would look something like this:

    doOneThing(yield Callback("key1"))
    andAnother(yield Callback("key2"))
    res1 = yield Wait("key1")
    res2 = yield Wait("key2")

True, you wouldn't get the syntactic sugar of the result variables - you would have to return them as an array or object with named properties. Lack of V8 support is of course the killer, and when I wrote my original comment, I for some reason assumed you'd modified V8 (at which point you may as well have implemented yield), but it turns out you just do the CPS transform in a preprocessing pass. Nice!

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