On Apr 29, 2015 11:49 AM, "Yury Selivanov" <yselivanov...@gmail.com> wrote: > > Hi Ethan, > > > On 2015-04-29 2:32 PM, Ethan Furman wrote: >> >> On 04/29, Yury Selivanov wrote: >>> >>> On 2015-04-29 1:25 PM, Ethan Furman wrote: >>>> >>>> cannot also just work and be the same as the parenthesized >>>> version. >>> >>> Because it does not make any sense. >> >> I obviously don't understand your position that "it does not make >> any sense" -- perhaps you could explain a bit? >> >> What I see is a suspension point that is waiting for the results of >> coro(), which will be negated (and returned/assigned/whatever). >> What part of that doesn't make sense? >> > > Because you want operators to be resolved in the > order you see them, generally. > > You want '(await -fut)' to: > > 1. Suspend on fut; > 2. Get the result; > 3. Negate it. > > This is a non-obvious thing. I would myself interpret it > as: > > 1. Get fut.__neg__(); > 2. await on it. > > So I want to make this syntactically incorrect:
As a bystander, I don't really care either way about whether await -fut is syntactically valid (since like you say it's semantically nonsense regardless and no one will ever write it). But I would rather like to actually know what the syntax actually is, not just have a list of examples (which kinda gives me perl flashbacks). Is there any simple way to state what the rules for parsing await are? Or do I just have to read the parser code if I want to know that? (I suspect this may also be the impetus behind Greg's request that it just be treated the same as unary minus. IMHO it matters much more that the rules be predictable and teachable than that they allow or disallow every weird edge case in exactly the right way.) -n
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