The "staging" thing was my misinterpretation of an error message. That's resolved. Levity polymorphism of these primops *seems* to be a fundamental consequence of the deeply-entrenched assumption that the exceptional path is the slow path. Catching and masking operations appear (to my untrained eye) to stick some stuff on the stack and then just jump to the user-provided function as a tail call. The complicated operation is actually raiseIO#, and that one doesn't *have* a result to manipulate. Again, testing is certainly required anyway, and I can add comments.
On Mon, Oct 5, 2020, 6:28 AM Simon Peyton Jones <simo...@microsoft.com> wrote: > You would have to be pretty careful to make them open-kinded. You'd need > to make sure that the implementation of these primops (which is quite > complicated) never touches or moves that result value. Maybe it is so, and > if so it'd be useful -- but should be *prominently* document in the RTS C > code that implements them. > > I'm afraid I don't know what "some kind of staging issue" is. > > Simon > > | -----Original Message----- > | From: ghc-devs <ghc-devs-boun...@haskell.org> On Behalf Of David Feuer > | Sent: 02 October 2020 21:43 > | To: ghc-devs <ghc-devs@haskell.org> > | Subject: Help making exception-related primops open-kinded > | > | I'm pretty sure raiseIO#, catch#, maskAsyncExceptions#, and so on can > | have open-kinded results. For example, we currently have > | > | catch# > | :: (State# RealWorld -> (# State# RealWorld, a #) ) > | -> (b -> State# RealWorld -> (# State# RealWorld, a #) ) > | -> State# RealWorld > | -> (# State# RealWorld, a #) > | > | but I think we *should* be able to have > | > | catch# > | :: (State# RealWorld -> (# State# RealWorld, o #) ) > | -> (b -> State# RealWorld -> (# State# RealWorld, o #) ) > | -> State# RealWorld > | -> (# State# RealWorld, o #) > | > | This should allow us to avoid boxing things just to be able to get > | them out of a `catch#` or `maskAsyncExceptions#` block. But when I > | tried just changing the types in primops.txt.pp, I got a type mismatch > | error that seems to suggest some sort of GHC build staging issue. How > | can I work around this? See > | https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgitl > | ab.haskell.org%2Fghc%2Fghc%2F- > | %2Fmerge_requests%2F4192%2Fdiffs&data=02%7C01%7Csimonpj%40microsof > | t.com%7C249daeec340348eae7a208d86713c76c%7C72f988bf86f141af91ab2d7cd01 > | 1db47%7C1%7C0%7C637372681930831064&sdata=y3czpdaLEC5TVJD3EAbiDN3cH > | PDJfA5%2BnfQnFrU%2Bs3E%3D&reserved=0 for my > | attempt. > | _______________________________________________ > | ghc-devs mailing list > | ghc-devs@haskell.org > | https://nam06.safelinks.protection.outlook.com/?url=http%3A%2F%2Fmail. > | haskell.org%2Fcgi-bin%2Fmailman%2Flistinfo%2Fghc- > | devs&data=02%7C01%7Csimonpj%40microsoft.com%7C249daeec340348eae7a2 > | 08d86713c76c%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637372681930 > | 831064&sdata=PRcbOsfSWbmNT2GTPQjPQqU2c1Fh%2FpHezIRz7Z9pE6c%3D& > | reserved=0 >
_______________________________________________ ghc-devs mailing list ghc-devs@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs
