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Request for review of proposed strict-concurrency improvements
by Yitzchak Gale 19 Jan '19

19 Jan '19

During the past few days, David Feuer has proposed a number of improvements to the strict-concurrency library. Thanks very much for this work! That, in turn, was triggered by some ideas of Eric Crockett - again, thanks very much for this! Since there are some subtle nuances at play here, I am asking the community to give this a brief review. Please comment directly in the PRs or issues, links below, not here on the list. Absent any comments, I will merge these PRs in about a week. If it's needed sooner than that, please let me know. Thanks, Yitz PRs: https://github.com/ygale/strict-concurrency/pull/9 https://github.com/ygale/strict-concurrency/pull/10 Issues: https://github.com/ygale/strict-concurrency/issues/2 https://github.com/ygale/strict-concurrency/issues/3 https://github.com/ygale/strict-concurrency/issues/4 https://github.com/ygale/strict-concurrency/issues/5 https://github.com/ygale/strict-concurrency/issues/6 https://github.com/ygale/strict-concurrency/issues/7 https://github.com/ygale/strict-concurrency/issues/8

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Re: Asynchronous exceptions in threadWait
by Bev 17 Jan '19

17 Jan '19

Who are all you people and why am I receiving emails from you? Please stop. Take me off list. Thanks On Thursday, January 17, 2019 Andrew Martin <andrew.thaddeus(a)gmail.com> wrote: Ah, that makes sense. They certainly differ in the guarantees they provide around when unregisterFd_ is called. Although I think the exception would still be raised in the caller of threadWait regardless of which way it was written. Sent from my iPhone > On Jan 17, 2019, at 5:58 PM, Michael Walker <mike(a)barrucadu.co.uk> wrote: > > So, something like this? > > threadWait :: Event -> Fd -> IO () > threadWait evt fd = do > (m, mgr, reg) <- mask_ $ do > m <- newEmptyMVar > mgr <- getSystemEventManager_ > reg <- registerFd mgr (\_ e -> putMVar m e) fd evt M.OneShot > pure (m, mgr, reg) > evt' <- takeMVar m `onException` unregisterFd_ mgr reg > if evt' `eventIs` evtClose > then ioError $ errnoToIOError "threadWait" eBADF Nothing Nothing > else return () > > I'm not sure this is semantically equivalent. > > GHC can pre-empt a thread whenever it allocates memory, and I assume > it can deliver exceptions at that granularity too. So if > `onException` allocates memory before the exception handler is set up, > then an exception could possibly be delivered in that brief window, > which would result in `unregisterFd_ mgr reg` never being called, and > an exception being raised in the caller of `threadWait`. > >> On Thu, 17 Jan 2019 at 22:43, Andrew Martin <andrew.thaddeus(a)gmail.com> wrote: >> >> Thanks. That makes sense. So, in the code I’m looking at, since takeMVar is the last effectful thing that happens, there is no semantic difference between having mask_ extend all the way down to the bottom of the block (as it currently does) and cutting it off right before the line involving takeMVar? >> >> Sent from my iPhone >> >> On Jan 17, 2019, at 5:23 PM, Michael Walker <mike(a)barrucadu.co.uk> wrote: >> >>>> Although the entire function has asynchronous exceptions masked, the call to takeMVar uses onException to deal with the possibility of an exception. According to the docs in Control.Concurrent, takeMVar can throw exceptions. But my understand (which may be wrong) is that the only exception this could throw would be something like BlockedIndefinitelyOnMVar, which I don't believe can happen here. >>> >>> That's not quite right. The mask_ function blocks asynchronous >>> exceptions from being delivered to the thread while it's not >>> "interruptible". Most blocking functions, such as takeMVar, make the >>> thread interruptible while they're blocked. So any asynchronous >>> exception (such as ThreadKilled) could be delivered to the thread if >>> it blocks in the takeMVar. >>> >>> -- >>> Michael Walker (http://www.barrucadu.co.uk) > > > > -- > Michael Walker (http://www.barrucadu.co.uk) _______________________________________________ Libraries mailing list Libraries(a)haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/libraries

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Asynchronous exceptions in threadWait
by Andrew Martin 17 Jan '19

17 Jan '19

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Re: taking over `bitvec`, `gamma`, `hs-hd5f` etc.
by Marco Zocca 17 Jan '19

17 Jan '19

Hi all, I had also tried recently to contact James Cook regarding maintainership of `gamma` (https://github.com/mokus0/gamma/pull/4) and three years ago about `hs-hdf5` (https://github.com/mokus0/hs-hdf5/issues/4#issuecomment-244511986) but he seldom checks email and github issues it seems. First of all, I hope he is well, and second, I once more volunteer to help with the maintenance of these packages. Best, Marco > Today's Topics: > > 1. Taking over maintainership of bitvec (Andrew Lelechenko) > > I would like to take over `bitvec` package > (https://hackage.haskell.org/package/bitvec) > > Unfortunately, the source code has not been updated for years and the > test suite does not build nowadays. There are also known issues. I > have prepared patches and tried to reach its maintainer James Cook > (cced) by email, but have not heard back. > > There was a takeover of another James' package in October 2018 > (https://mail.haskell.org/pipermail/libraries/2018-October/029062.html) > In that case James appeared to be out of reach. > > -- > Best regards, > Andrew >

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Taking over maintainership of bitvec
by Andrew Lelechenko 16 Jan '19

16 Jan '19

I would like to take over `bitvec` package (https://hackage.haskell.org/package/bitvec) Unfortunately, the source code has not been updated for years and the test suite does not build nowadays. There are also known issues. I have prepared patches and tried to reach its maintainer James Cook (cced) by email, but have not heard back. There was a takeover of another James' package in October 2018 (https://mail.haskell.org/pipermail/libraries/2018-October/029062.html) In that case James appeared to be out of reach. -- Best regards, Andrew

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How about a "deriving defaulted" deriving strategy
by Andrew Martin 14 Jan '19

14 Jan '19

I was just doing the usual incantation for an exception type: data DatagramException = ... deriving stock (Eq,Show) instance Exception Datagram And it suddenly hit me what a shame it was that I cannot put the Exception instance in a deriving clause like the others. It would be more visually pleasing to write: data DatagramException = ... deriving stock (Eq,Show) deriving defaulted (Exception) -- -Andrew Thaddeus Martin

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Data.List.maximumBy uses counter-intuitive ordering
by Johannes Waldmann 08 Jan '19

08 Jan '19

Dear all, this was brought up on the GHC tracker (not by me) https://ghc.haskell.org/trac/ghc/ticket/15921 and it was suggested for discussion here. my summary: Data.List.maximumBy is right-biased, minimumBy is left-biased, and none of this is documented. - J.W.

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Crazy suggestion: ByteString -> Bytes
by Merijn Verstraaten 08 Jan '19

08 Jan '19

Ok, so I think there is a fairly wide consensus that the name ByteString is a pretty misleading historical naming mistake. On the other hand, I also realise bytestring is at the very core of the Haskell ecosystem and any breakage has to be avoided at all cost... So I was just wondering on IRC what (if any?) problems we'd run into if we released a "bytes" package that's just s/ByteString/Bytes of bytestring (Data.Bytes, Bytes type, etc) then turn bytestring into a hollow shell that just re-exports Data.Bytes as Data.ByteString, etc. and defines "type ByteString = Bytes". I realise there's no way we'll get rid of bytestring itself any time soon (if ever), but at least we could point new code and beginners at a less confusingly named type. Added bonus Bytes is considerably shorter to type! Cheers, Merijn

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re: cabal bootstrap
by Harley Leyton 07 Jan '19

07 Jan '19

Output is the same as in https://github.com/haskell/cabal/issues/5391 [ 1 of 215] Compiling Distribution.Compat.Binary ( Distribution/Compat/Binary.hs, Distribution/Compat/Binary.o ) [ 2 of 215] Compiling Distribution.Compat.Directory ( Distribution/Compat/Directory.hs, Distribution/Compat/Directory.o ) [ 3 of 215] Compiling Distribution.Compat.Exception ( Distribution/Compat/Exception.hs, Distribution/Compat/Exception.o ) [ 4 of 215] Compiling Distribution.Compat.Internal.TempFile ( Distribution/Compat/Internal/TempFile.hs, Distribution/Compat/Internal/TempFile.o ) [ 5 of 215] Compiling Distribution.Compat.MonadFail ( Distribution/Compat/MonadFail.hs, Distribution/Compat/MonadFail.o ) [ 6 of 215] Compiling Distribution.Compat.Newtype ( Distribution/Compat/Newtype.hs, Distribution/Compat/Newtype.o ) [ 7 of 215] Compiling Distribution.Compat.Semigroup ( Distribution/Compat/Semigroup.hs, Distribution/Compat/Semigroup.o ) [ 8 of 215] Compiling Distribution.Compat.Stack ( Distribution/Compat/Stack.hs, Distribution/Compat/Stack.o ) [ 9 of 215] Compiling Distribution.Compat.Prelude ( Distribution/Compat/Prelude.hs, Distribution/Compat/Prelude.o ) [ 10 of 215] Compiling Distribution.Compat.ReadP ( Distribution/Compat/ReadP.hs, Distribution/Compat/ReadP.o ) [ 11 of 215] Compiling Distribution.Compat.Parsing ( Distribution/Compat/Parsing.hs, Distribution/Compat/Parsing.o ) [91m [0m[91mDistribution/Compat/Parsing.hs:61:1: error: [0m[91m Could not find module[0m[91m `Text.Parsec' [0m[91m Use -v to see a list of the files searched for. [0m[91m | 61 | import qualified Text.Parsec as Parsec [0m[91m | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ [0m[ 12 of 215] Compiling Distribution.Compat.Graph ( Distribution/Compat/Graph.hs, Distribution/Compat/Graph.o ) [ 13 of 215] Compiling Distribution.Compat.GetShortPathName ( Distribution/Compat/GetShortPathName.hs, Distribution/Compat/GetShortPathName.o ) [ 14 of 215] Compiling Distribution.Compat.DList ( Distribution/Compat/DList.hs, Distribution/Compat/DList.o ) [ 15 of 215] Compiling Distribution.Compat.Lens ( Distribution/Compat/Lens.hs, Distribution/Compat/Lens.o ) [91m [0m[91mDistribution/Compat/Lens.hs:55:1: error:[0m[91m Could not find module `Control.Monad.State.Class' Perhaps you meant Control.Monad.Trans.Class (from transformers-0.5.2.0) Control.Monad.IO.Class (from base-4.10.0.0) Use -v to see a list of the files searched for. | 55 | import Control.Monad.State.Class (MonadState (..), gets, modify) | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ > Do you have the output or something? I recall that the bootstrap.sh > script worked last time I tried it. Perhaps GHC used to ship with parsec > and now it doesn't? > > If you provide some broader context I may be able to help - if you're > porting cabal to a new platform you may consider cross-compiling cabal > > On 1/6/19 7:08 AM, Harley Leyton wrote: >> Is there any way to install cabal-install on top of a fresh installation of ghc with bootsrap.sh? I keep getting stuck on https://github.com/haskell/cabal/issues/5391. >> Libraries mailing list >> Libraries at haskell.org> http://mail.haskell.org/cgi-bin/mailman/listinfo/libraries

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cabal bootsrap
by Harley Leyton 06 Jan '19

06 Jan '19

Is there any way to install cabal-install on top of a fresh installation of ghc with bootsrap.sh? I keep getting stuck on https://github.com/haskell/cabal/issues/5391.

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