http://blog.gmane.org/gmane.comp.lang.haskell.libraries hourly 1 1901-01-01T00:00+00:00 http://gmane.org/img/gmane-25t.png http://gmane.org http://comments.gmane.org/gmane.comp.lang.haskell.libraries/19482 <pre>Hello libraries, it's on! Time to tackle the Applicative-Monad issue, hopefully once and for all. Over the last couple of weeks I've looked through previous proposals, asked #haskell about their opinions, and compiled it all into one file that sums up what I made of that. It's a bit long for an email and uses markdown, so I'll just provide links at the end of this mail instead of pasting it in here. In there, the whole thing and how to approach it is explained in more detail. Here's an abstract of what it the proposal consists of: - Don't break compatibility - Apply it gently - Applicative m =&gt; Monad m - Applicative into Prelude (and therefore into the Report) - (Alternative m, Monad m) =&gt; MonadPlus m - Promote `join` into the Monad typeclass Let's make this happen! I'm going to give a ballpark discussion period of four weeks, but since I can imagine this discussion could become quite complex we shouldn't take it too serious. I'll summarize what's been going on periodically though. David Links: Th</pre> David Luposchainsky 2013-05-23T19:39:17 http://comments.gmane.org/gmane.comp.lang.haskell.libraries/19467 <pre>This "burning bridges" thread has really got us going! I'm a bit concerned, though, that we don't have an effective mechanism for resolving such debates. If everyone feels that they have a vote, perhaps, but only one among many, then one feels either mandated or indeed willing to invest the extra cycles to summarise pros and cons based on feedback, crisply articulate alternatives, and so on. And, worse still, no one feels mandated to actually decide anything. That's fine when there's a clear consensus; not so fine when there isn't, as here. Several people on the "Burning bridges" thread have commented on the interminable nature of the debate. Our general procedures for library changes are described here: http://www.haskell.org/haskellwiki/Library_submissions. For specialised libraries (eg MD5 checksum, or even containers) the situation is clear: the author or current maintainer decides. But for the basic core libraries, whose influence is pervasive, matters are murkier. Looking at http://www.has</pre> Simon Peyton-Jones 2013-05-23T07:48:22 http://comments.gmane.org/gmane.comp.lang.haskell.libraries/19434 <pre> Here are the current totals by my count, ignoring any 0s: +13 / -0 +1 / -11 +0 / -12 +0 / -13 - C. </pre> Casey McCann 2013-05-22T19:01:13 http://comments.gmane.org/gmane.comp.lang.haskell.libraries/19392 <pre>The Mac OS X RC3 installers are up: Haskell Platform 2013.2.0.0 32bit rc3.signed.pkg&lt;http://www.ozonehouse.com/mark/platform/Haskell%20Platform%202013.2.0.0%2032bit%20rc3.signed.pkg&gt; Haskell Platform 2013.2.0.0 64bit rc3.signed.pkg&lt;http://www.ozonehouse.com/mark/platform/Haskell%20Platform%202013.2.0.0%2064bit%20rc3.signed.pkg&gt; Only difference in these from RC2 is that the missing documentation for network, random, and primitive has been restored. These will be the final, barring any catastrophic issue. — Mark 15dd8762c9800308cb7cfdd16ea1a8e74988e06a Haskell Platform 2013.2.0.0 32bit rc3.signed.pkg 89e6fb747816af69acabc5c04cee103257855614 Haskell Platform 2013.2.0.0 64bit rc3.signed.pkg _______________________________________________ Libraries mailing list Libraries&lt; at &gt;haskell.org http://www.haskell.org/mailman/listinfo/libraries </pre> Mark Lentczner 2013-05-21T16:15:58 http://comments.gmane.org/gmane.comp.lang.haskell.libraries/19373 <pre>I want to apologize to wren (and everybody else). I was tired and overreacted when the discussion started veering into making more breaking changes. I don't mind the Foldable changes too much. My main concerns are: * loss of monomorphism makes teaching more difficult * They can be generalized in other useful ways However, I don't consider those concerns show-stoppers. </pre> Gabriel Gonzalez 2013-05-21T05:41:31 http://comments.gmane.org/gmane.comp.lang.haskell.libraries/19370 <pre>lets see what concerns there are 1) will any code break? Nope! In fact, it's trivial to provide a shim that only exposes the list monomorphic versions. 2) does the change make learning the language more challenging? No. In fact, i've encountered *many* more smart people getting confused as to why the map / fold etc in prelude are all list specific than i've seen people struggle with type classes. The various list specific versions of the foldable codes actually **confuses** smart software folks who are starting to learn haskell for fun. I can't explain to a smart engineer *any* reason why minimum :: Ord&lt;http://www.haskell.org/ghc/docs/latest/html/libraries/base/Prelude.html#t:Ord&gt; a =&gt; [a] -&gt; a exists in prelude. I *can* explain why something like minimum :: (Foldable&lt;http://www.haskell.org/ghc/docs/latest/html/libraries/base/Data-Foldable.html#t:Foldable&gt; t, Ord&lt;http://www.haskell.org/ghc/docs/latest/html/libraries/base/Data-Ord.html#t:Ord&gt; a) =&gt; t a -&gt; a would be useful and deserving of being in the </pre> Carter Schonwald 2013-05-21T05:06:18 http://comments.gmane.org/gmane.comp.lang.haskell.libraries/19366 <pre>Hi all, I've uploaded the RC1 2013.2.0.0 release candidate installer to http://code.haskell.org/~refold/HaskellPlatform-2013.2.0.0-rc1-setup.exe SHA1: fe9a4eee2fe8839eb3b240f15a2af229a110e37f What's new in 2013.2.0.0-rc1: * Updated versions of all packages Known issues: * OpenGL-related libraries are compiled without -split-objs because of GHC performance issues. * Also see http://trac.haskell.org/haskell-platform/wiki/Windows Unless someone finds serious bugs in this RC, it can be released unchanged. Enjoy! </pre> Mikhail Glushenkov 2013-05-21T00:00:15 http://comments.gmane.org/gmane.comp.lang.haskell.libraries/19333 <pre>On some haskell list I read that for lists, mapM_ f l is more space-efficient that just void $ mapM f l Any reason why mapM_ is missing from Data.Traversable? Cheers, Andreas </pre> Andreas Abel 2013-05-18T21:21:53 http://comments.gmane.org/gmane.comp.lang.haskell.libraries/19300 <pre>Hello everyone, I recently went through GHC's source, and discovered there are quite a few instances of Monad that don't have Functor or Applicative instances. Fixing this is very easy by adding the standard instances (pure = return etc.), and will not break code. There is one exception to this: Hoopl defines its own (&lt;*&gt;). However, since it does not seem to have any packages depend on it otherwise, renaming this operator is also easily done (the thing is only used ten times or so). I called it (&lt;*|*&gt;) to complement (|*&gt;&lt;*|), but naming should be the least important issue here. Small piece of backstory: The idea behind this is making GHC future-proof for changing Applicative to be a superclass of Monad. However, I think adding the Applicative instances is a good idea regardless of whether this will ever happen, so that's the only thing I'm proposing right now. Greetings, David </pre> David Luposchainsky 2013-05-16T11:33:44 http://comments.gmane.org/gmane.comp.lang.haskell.libraries/19285 <pre>Hi, I'm trying to expose some byte swapping (bSwap) capabilities in base, namely operation to allow to swap endianness on word{16,32,64}, i.e.: bswap16 :: Word16 -&gt; Word16 bswap16 a = (a `shiftR` 8) .|. (a `shiftL` 8) ... I'ld want to propose to extends Bits to do so generically: class Bits a where ... bSwap : a -&gt; a I'm attaching a patch that do as explained, and add a default implementation for bSwap, so that compatibility is assured for existing instances. </pre> Vincent Hanquez 2013-05-16T06:59:28 http://comments.gmane.org/gmane.comp.lang.haskell.libraries/19266 <pre>Hello all, While looking through the pull requests for stm-chans I came across a discrepancy in the new stm. Namely, we have the following definitions: * stm == 2.4 newBroadcastTChan :: STM (TChan a) newBroadcastTChan = do dummy_hole &lt;- newTVar TNil write_hole &lt;- newTVar TNil read &lt;- newTVar dummy_hole write &lt;- newTVar write_hole return (TChan read write) newBroadcastTChanIO :: IO (TChan a) newBroadcastTChanIO = do dummy_hole &lt;- newTVarIO TNil write_hole &lt;- newTVarIO TNil read &lt;- newTVarIO dummy_hole write &lt;- newTVarIO write_hole return (TChan read write) * stm == 2.4.2 newBroadcastTChan :: STM (TChan a) newBroadcastTChan = do write_hole &lt;- newTVar TNil read &lt;- newTVar (error ...) write &lt;- newTVar write_hole return (TChan read write) newBroadcastTChanIO :: IO (TChan a) newBroadcastTChanIO = do dummy_hole &lt;- newTVarIO TNil write_hole &lt;- newTVarIO </pre> wren ng thornton 2013-05-13T05:24:57 http://comments.gmane.org/gmane.comp.lang.haskell.libraries/19265 <pre>-------------------------------------------- </pre> wren ng thornton 2013-05-13T04:35:17 http://comments.gmane.org/gmane.comp.lang.haskell.libraries/19260 <pre>*We are in the home stretch for Haskell Platform 2013.2!* The Mac OS X RC2 installers are up: Haskell Platform 2013.2.0.0 32bit rc2.signed.pkg&lt;http://www.ozonehouse.com/mark/platform/Haskell%20Platform%202013.2.0.0%2032bit%20rc2.signed.pkg&gt; Haskell Platform 2013.2.0.0 64bit rc2.signed.pkg&lt;http://www.ozonehouse.com/mark/platform/Haskell%20Platform%202013.2.0.0%2064bit%20rc2.signed.pkg&gt; Only real difference in these from RC1 is packaging: the Cabal doc is now included. There is no update to source tarball RC1, which is still there too. I expect these to be renamed the official release within a week. *Packagers:* Please produce Release Candidates. The package version list shouldn't change, unless any of you find an issue. - Mark _______________________________________________ Libraries mailing list Libraries&lt; at &gt;haskell.org http://www.haskell.org/mailman/listinfo/libraries </pre> Mark Lentczner 2013-05-11T17:55:42 http://comments.gmane.org/gmane.comp.lang.haskell.libraries/19233 <pre>I would like to propose the addition of whenJust :: Monad m =&gt; Maybe a -&gt; (a -&gt; m ()) -&gt; m () whenJust (Just x) f = f x whenJust _ _ = return () to Control.Monad, in the section "Conditional execution of monadic expressions" next to guard :: MonadPlus m =&gt; Bool -&gt; m () when :: Monad m =&gt; Bool -&gt; m () -&gt; m () unless :: Monad m =&gt; Bool -&gt; m () -&gt; m () Why? It would allow us to write more readable code and fit well into the group of similar functions of this style. Compare mUser &lt;- lookupUser whenJust mUser email or whenJust mUser $ \user -&gt; do putStrLn "Mailing!" email user with some currently available alternatives: case mUser of Just user -&gt; do putStrLn "Mailing!" email user Nothing -&gt; return () (Default base case clutter.) import Data.Foldable forM_ mUser $ \user -&gt; do putStrLn "Mailing!" email user (Not too intuitive/well-named here and "Ambiguous occurrence forM_" clash with Control.Monad.) </pre> Niklas Hambüchen 2013-05-10T06:13:45 http://comments.gmane.org/gmane.comp.lang.haskell.libraries/19230 <pre>The Mac OS X installers for HP 2013.2 RC 1 are up: Haskell Platform 2013.2.0.0 32bit rc1.signed.pkg&lt;http://www.ozonehouse.com/mark/platform/Haskell%20Platform%202013.2.0.0%2032bit%20rc1.signed.pkg&gt; Haskell Platform 2013.2.0.0 64bit rc1.signed.pkg&lt;http://www.ozonehouse.com/mark/platform/Haskell%20Platform%202013.2.0.0%2064bit%20rc1.signed.pkg&gt; This corresponds to what is currently checked in to the pre-release branch on github: https://github.com/haskell/haskell-platform/tree/pre-release There is at least one small wibble with these: The cabal documentation is missing. So I expect at least one small turn before final release.... but this is pretty close. - Mark _______________________________________________ Libraries mailing list Libraries&lt; at &gt;haskell.org http://www.haskell.org/mailman/listinfo/libraries </pre> Mark Lentczner 2013-05-08T07:41:21 http://comments.gmane.org/gmane.comp.lang.haskell.libraries/19226 <pre>The current build of the platform has grown over the years to a somewhat convoluted collection of shell scripts, makefiles, autoconf, and some custom Haskell. It is further complicated by three distinct stages: making the source distribution, building the packages, bundling for distribution. Lastly, I suspect that each distribution (Mac, Windows, and n × unix-like) has it's own path through these stages. I've done some amount of rework on the process over the last two years, but I'm thinking it is time for wholesale replacement. I'm considering using Shake &lt;http://community.haskell.org/~ndm/shake/&gt; to replace all three stages as one build. Distributions could choose to either re-cast their process into this Shake program, or work from the source distribution. The source distribution currently contains scripts and other bits for generically building the platform from source. I currently have no way to know which parts of those bits people rely on for their distributions. This transition would substantially</pre> Mark Lentczner 2013-05-05T15:55:34 http://comments.gmane.org/gmane.comp.lang.haskell.libraries/19225 <pre>The source tar-ball for HP 2013.2 RC 1 is up: http://www.ozonehouse.com/mark/platform/haskell-platform-2013.2.0.0-rc1.tar.gz This corresponds to what is currently checked in to the pre-release branch on github: https://github.com/haskell/haskell-platform/tree/pre-release *Packagers:* Please produce an RC1 candidate from the above. I'm having some trouble producing a Mac release (Xcode woes again...) but expect it in a few days. — Mark _______________________________________________ Libraries mailing list Libraries&lt; at &gt;haskell.org http://www.haskell.org/mailman/listinfo/libraries </pre> Mark Lentczner 2013-05-05T15:37:13 http://comments.gmane.org/gmane.comp.lang.haskell.libraries/19214 <pre>There is a list of problems with the current "Map" and "IntMap" modification interfaces: - they are filled with quirky and too specialized functions - they are not consistent in terms of how equally named functions behave: http://hackage.haskell.org/packages/archive/containers/latest/doc/html/Data-IntMap-Strict.html#v:updateLookupWithKey - they still don't cover some important scenarios of use Because of the above I have very often found myself in requirement for the following function: withItem :: (Ord k) =&gt; k -&gt; (Maybe i -&gt; (r, Maybe i)) -&gt; Map k i -&gt; (r, Map k i) withItem k f m = let item = Map.lookup k m (r, item') = f item m' = Map.update (const item') k m in (r, m') It covers all the imaginable scenarios of modification operations: delete, update, replace, - yet it also provides one with ability to extract the modified data and not only. The problem is that this implementation involves a repeated lookup for the same item: first wi</pre> Nikita Volkov 2013-04-30T13:18:48 http://comments.gmane.org/gmane.comp.lang.haskell.libraries/19210 <pre> Hi all, Currently, if you try to use rawSystem to run a program that doesn't exist, you will just get a bad error code as a result, e.g. this program: import System.IO.Error import System.Process main :: IO () main = do (rawSystem "/bin/true" [] &gt;&gt;= print) `catchIOError` \e -&gt; putStrLn ("Exc: " ++ show e) (rawSystem "/bin/false" [] &gt;&gt;= print) `catchIOError` \e -&gt; putStrLn ("Exc: " ++ show e) (rawSystem "/non/existent" [] &gt;&gt;= print) `catchIOError` \e -&gt; putStrLn ("Exc: " ++ show e) putStrLn "Done" prints: ExitSuccess ExitFailure 1 ExitFailure 127 Done However, if we are on a platform that supports vfork, then we can pass information from the child process back to the parent process as they share address space. With the attached patch we instead get: ExitSuccess ExitFailure 1 Exc: resolveProcessHandle: does not exist (No such file or directory) (and it should be easy t</pre> Ian Lynagh 2013-04-28T13:36:24 http://comments.gmane.org/gmane.comp.lang.haskell.libraries/19202 <pre>Hi all, I would like to add a derived MonadPlus instance for both Rand and RandT. Also, since it seems that MonadRandom has no maintainer I propose to take on its maintainership. Any comments/objections/etc. welcome. -Brent </pre> Brent Yorgey 2013-04-24T18:38:01 http://comments.gmane.org/gmane.comp.lang.haskell.libraries/19199 <pre>Hello lists, I'm pleased to announce the first release of data-textual[1], a library that provides human-friendly counterparts (called Printable/Textual) of the compiler-friendly Show/Read type classes. The library is intended to be used for printing and parsing of non-compound and non-polymorphic compound data (e.g. numbers, network and hardware addresses, date/time, etc). A quick example (vs network-ip[2] library): λ&gt; import Data.Maybe (fromJust) λ&gt; import Data.Textual λ&gt; import Network.IP.Addr λ&gt; let x = fromString "[dead::b:e:e:f]:123" :: Maybe Inet6Addr λ&gt; x Just (InetAddr {inetHost = ip6FromWords 0xdead 0x0 0x0 0x0 0xb 0xe 0xe 0xf, inetPort = 123}) λ&gt; toString (fromJust x) "[dead::b:e:e:f]:123" λ&gt; let y = fromStringAs aNet4Addr "192.168.100.1/24" λ&gt; y Just (netAddr (ip4FromOctets 192 168 100 1) 24) λ&gt; toText (netPrefix $ fromJust y) "192.168.100.0" [1] http://hackage.haskell.org/package/data-textual [2] http://hackage.haskell.org/package/network-ip ________________________________</pre> Mikhail Vorozhtsov 2013-04-24T06:18:51 Search the mailing list at Gmane query http://search.gmane.org/?group=$group=gmane.comp.lang.haskell.libraries