Simon Marlow

I have no strong opinions here.

I've just uploaded 0.3.4.4 which switches the ParIO monad over to the Trace scheduler too.

I'm not sure I understand the motivation for this, and it adds a lot of complexity. Is there somem reason you can't use `Concurrently`?

Yes!

The alternative is to have `hashable` depend on `async`. I don't feel strongly either way, but if `hashable` already has a large set of dependencies perhaps this is the better...

> You could add it as an optionally built module + dep via cabal flag? No, that's even worse. Packages should have a stable API. How would you express a...

Bear in mind that it will have cost O(n). If you're ok with that, and there's a valid use case, I suppose I don't have any objections.

I'd like to accept this PR but a few things remain: * expose representations from an internal module * fix the conflicts * we should really set up Travis so...

I agree. CC @snoyberg

I suggest we have a `cancelMany` that cancels multiple asyncs concurrently, and then use it everywhere we do multiple cancels, like `waitAnyCancel`.