- Libraries - Haskell.org

Re: [Hugs] #49: LDFLAGS and hugs packages on OS X 10.4
by Ross Paterson 24 Nov '06

24 Nov '06

On Fri, Nov 24, 2006 at 10:30:16AM -0000, Hugs wrote: > #49: LDFLAGS and hugs packages on OS X 10.4 > The value of the environnment variable LDFLAGS is not used to compile > hug's packages. Consequently, make fails to build X11 package (on OS X > 10.4.8) > [...] > My LDFLAGS variable whose value is "-L/usr/X11R6/lib -L/Users/julien/local/lib" has not been used. > Simply add -L/usr/X11R6/lib to the gcc command and it compile fine. This is really an issue between Cabal and the packages. I presume it's expected that LDFLAGS will be used because configure uses it. So should Cabal use LDFLAGS, or should packages that use autoconf add LDFLAGS to ld-options?

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portability of Data.ByteString.Lazy
by Ross Paterson 24 Nov '06

24 Nov '06

Data.ByteString.Lazy defines ByteString as a type synonym, and then uses that in instances, which isn't permitted by Haskell 98. How about defining a newtype ByteString in Data.ByteString.Lazy.Base instead?

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ANNOUNCE: PQC: QuickCheck in the Age of Concurrency
by dons＠cse.unsw.edu.au 24 Nov '06

24 Nov '06

------------------------------------------------------------------------ PQC: QuickCheck in the Age of Concurrency An SMP parallel QuickCheck driver ------------------------------------------------------------------------ Do you: * Have (or want) lots of QuickCheck properties? * Run them often (maybe on every darcs commit)? * Tired of waiting for the testsuite to finish? * Got a multi-core box with cpus sitting idle...? Yes? You need Parallel QuickCheck! PQC provides a single module: Test.QuickCheck.Parallel. This is a QuickCheck driver that runs property lists as jobs in parallel, and will utilise as many cores as you wish, with the SMP parallel GHC 6.6 runtime. It is simple, scalable replacement for Test.QuickCheck.Batch. An example, on a 4 cpu linux server, running 20 quickcheck properties. With 1 thread only: $ time ./a.out 1 1: sort1 : OK, 1000 tests. 1: sort2 : OK, 1000 tests. 1: sort3 : OK, 1000 tests. 1: sort4 : OK, 1000 tests. ... ./a.out 1 > x 18.94s user 0.01s system 99% cpu 18.963 total 18 seconds, 99% cpu. But I've got another 3 2.80GHz processors sitting idle! Let's use them, to run the testsuite faster. No recompilation required. 4 OS threads, 4 Haskell threads: $ time ./a.out 4 +RTS -N4 > /dev/null ./a.out 4 +RTS -N4 > /dev/null 20.65s user 0.22s system 283% cpu 7.349 total 283% cpu, not bad. We're getting close to being limited by the length of the longest running test. Or on a dual core macbook, thanks to Spencer Janssen for macbook data and testing: 1 thread: ./Example 1 17.256s 2 threads: ./Example 2 +RTS -N2 10.402s Get it! Homepage: http://www.cse.unsw.edu.au/~dons/pqc.html Haddocks: http://www.cse.unsw.edu.au/~dons/pqc/ Example : http://www.cse.unsw.edu.au/~dons/code/pqc/examples/Example.hs darcs get http://www.cse.unsw.edu.au/~dons/code/pqc Happy, quick checking, Don

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Haskell Hackathon, Hac 07
by dons＠cse.unsw.edu.au 22 Nov '06

22 Nov '06

Apologies for multiple copies (some devs don't read haskell@ I've been informed) ------------------------------------------------------------------------ Hac 2007 The 2007 Haskell Hackathon January 10-12, 2007 Oxford University Computing Laboratory http://haskell.org/haskellwiki/Hac_2007 ------------------------------------------------------------------------ Following the success of the GHC Hackathon at ICFP, we are pleased to announce the inaugural Haskell Hackathon, Hac 2007! The event will be held over 3 days, January 10-12 2007, at the Oxford University Computing Laboratory, in the UK. The plan is to hack on Haskell infrastructure, tools, libraries and compilers. To attend please register, and get ready to hack those lambdas! Code to hack on: * Hackage * Cabal * Porting foreign libraries * Porting compilers * Bug squashing * Performance improvements to compilers * You decide! Registration: We ask that you register you interest. Follow the instructions on the registration page: http://haskell.org/haskellwiki/Hac_2007/Registration Numbers for the hackathon are limited to 20, due to room size constraints. Should space be available after the registration period ends, additional attendees may register on a first-come first-served basis. Important dates: Registration deadline: December 6th, 2006 Confirmation: December 10th, 2006 Hackathon: January 10-12, 2007 Organisers: Duncan Coutts Ian Lynagh Don Stewart

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Questions about the array APIs
by Iavor Diatchki 21 Nov '06

21 Nov '06

Hello, I have two questions about the array APIs in the libraries: 1. Is there a way to write an immutable array to a handle without using any unsafe methods? 2. Why does the function 'getBounds' (of the 'MArray' class) return its result in a monad? -Iavor

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Proposal: Adding Kleisli composition to Control.Monad
by dons＠cse.unsw.edu.au 17 Nov '06

17 Nov '06

http://hackage.haskell.org/trac/ghc/ticket/997 Add Kleisli composition to Control.Monad. Kleisli composition of monads is a foundational feature missing from the current Control.Monad library. A recent discussion revealed solid support for its inclusion. This patch adds: (>=>) :: (Monad m) => (a -> m b) -> (b -> m c) -> (a -> m c) (<=<) :: (Monad m) => (b -> m c) -> (a -> m b) -> (a -> m c) Along with the useful control combinator: forever :: (Monad m) => m a -> m () Traditionally, >=> has been written as @@, however to support the flipped version, new notation seems to be required. It should be notated that there is overlap with the Kleisli class in Control.Arrow (specifically >>>), however, short of a convenient unifying form for Arrow and Monad, a monad-specific >>> seems reasonable. To mirror >>> and =<<, infixr 1 was chosen. Proposal period: 2 weeks. Deadline: 27th November. -- Don ------------------------------------------------------------------------ hunk ./Control/Monad.hs 40 + , (>=>) -- :: (Monad m) => (a -> m b) -> (b -> m c) -> (a -> m c) + , (<=<) -- :: (Monad m) => (b -> m c) -> (a -> m b) -> (a -> m c) + , forever -- :: (Monad m) => m a -> m () hunk ./Control/Monad.hs 179 +infixr 1 <=<, >=> + +-- | Left-to-right Kleisli composition of monads. +(>=>) :: Monad m => (a -> m b) -> (b -> m c) -> (a -> m c) +f >=> g = \x -> f x >>= g + +-- | Right-to-left Kleisli composition of monads. '(>=>)', with the arguments flipped +(<=<) :: Monad m => (b -> m c) -> (a -> m b) -> (a -> m c) +(<=<) = flip (>=>) + +-- | @'forever' act@ repeats the action infinitely. +forever :: (Monad m) => m a -> m () +forever a = a >> forever a ------------------------------------------------------------------------

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darcs patch: Implementation of aton and ntoa outside ... (and 1 more)
by Robert Marlow 16 Nov '06

16 Nov '06

Mon Sep 25 16:55:55 JST 2006 Robert Marlow <bobstopper(a)bobturf.org> * Implementation of aton and ntoa outside the IO monad This is a second attempt at the earlier patch inet_ntoa and inet_aton can be implemented purely to avoid the need for the IO monad. Additionally, inet_addr is currently incorrect due to using the inet_addr C function which is considered obsolete due to incorrectly failing while converting 255.255.255.255 as an address. Mon Sep 25 17:12:52 JST 2006 Robert Marlow <bobstopper(a)bobturf.org> * Fixed bugs in names of aton and ntoa

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Data.List.join
by Josef Svenningsson 16 Nov '06

16 Nov '06

Hi, I'd like to propose to include the following function in Data.List: join :: [a] -> [[a]] -> [a] join x xs = concat (intersperse x xs) I find that every time I use intersperse I also concat the result. And it seems that I'm not alone: http://www.google.com/codesearch?q=file%3A%5C.hs+intersperse&btnG=Search+Co… A clear majority of all the uses of intersperse also use concat on the result. I think it seems worthwhile to give a name to that idiom. The name 'join' was taken from Data.ByteString, where a similar function exists. All the best, Josef Svenningsson

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Re: patch applied (packages/HaXml): Use ByteString for output (contributed by Jason Dagit, with modifications)
by Malcolm Wallace 15 Nov '06

15 Nov '06

[moved from cvs-libraries to reach a wider audience] Ian Lynagh <igloo(a)earth.li> wrote: > On Mon, Nov 13, 2006 at 10:46:14AM -0800, Malcolm Wallace wrote: > > * Use ByteString for output (contributed by Jason Dagit, with > > modifications) There are some new signatures in > > Text.XML.HaXml.XmlContent: > > fpsShowXml > > fpsWriteXml > > fpsHPutXml > > I think bs* would make more sense than fps*, OK, I can see your reasoning. Are there any other good suggestions out there? Normally, Data.ByteString users tend to put their operations in a separate module altogether, with the same function names as the normal String-based ops. Then it is easy to distinguish them by simple module import/qualification. In fact, that is how Jason originally implemented it - but I was unhappy about the huge amount of code duplication involved, which is why I choose a different route. I am open to further ideas about how to best achieve a similar effect (i.e. ByteString ops available, but minimal code duplication). Regards, Malcolm

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Re: darcs patch: forkChild, waitForChild, parIO, timeout
by Sebastian Sylvan 14 Nov '06

14 Nov '06

On 11/14/06, David Menendez <zednenem(a)psualum.com> wrote: > Peter Simons writes: > > > data TimeoutError = TimeoutError deriving (Show, Typeable) > > type Microseconds = Int > > > > timeout :: Microseconds -> IO a -> IO a > > This seems like a good place to use DiffTime, from Data.Time.Clock. That > way, you can specify timeouts using (fractional) seconds and avoid > confusion as to whether timeout uses microseconds, milliseconds, or > nanoseconds. > > Unforunately, Data.Time.Clock is in the time package. An alternative is > Micro, from Data.Fixed. Seems to me that the obvious choice is to use the proper SI unit of seconds, and pass it in as a Double (or have it be polymorphic and constrained to RealFrac). /S -- Sebastian Sylvan +46(0)736-818655 UIN: 44640862

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