Hmm, upon further thought regarding to exec's behavior on async exceptions, surely there are use cases for both a simple and timely abandonment of the connection and for attempting to cancel a long-running query while attempting to save the connection. In the latter case, I don't have anything too concrete in mind, but surely it exists.

One obvious solution would be to use two different async exceptions. Perhaps a ThreadKilled exception would simply abort while a Timeout exception would trigger the cancel behavior. But reviewing the source of System.Timeout, Timeout is not exported from the module, which would seem to rule out that behavior.... so maybe we need to define a separate Cancel exception.

One question I'd have is whether or not this type of behavior would compose well: e.g. could you lift it through postgresql-simple with a minimum of fuss, or would the cancel behavior of query_ and execute_ be a little off?

Another possible solution would be to define a combinator that deals with Cancel exceptions.

Best,

Leon