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GHC: compile using multiple cores?
by Peter Verswyvelen 10 Apr '09

10 Apr '09

Is it possible to use all CPU cores when compiling with GHC and/or Cabal?

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ANN: network-bytestring 0.1.2
by Johan Tibell 10 Apr '09

10 Apr '09

I am pleased to announce a new release of network-bytestring, a Haskell library for fast socket I/O using ByteStrings. New in this release is support for scatter/gather I/O (also known as vectored I/O). Scatter/gather I/O provides more efficient I/O by using one system call to send several separate pieces of data and by avoiding unnecessary copying. I would like to thank Brian Lewis, Bryan O'Sullivan, and Thomas Schilling for contributing patches for this release. Get it: cabal install network-bytestring And on Hackage: http://hackage.haskell.org/cgi-bin/hackage-scripts/package/network-bytestri… Windows hackers needed: I've made sure that the library builds on Windows but since I don't use Windows myself I haven't implemented scatter/gather I/O support for Windows. It should be straightforward to add and I'd be happy to review the patches. Cheers, Johan

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ghci *.hs
by Paul Keir 09 Apr '09

09 Apr '09

Hi all, I like to use ghci *.hs to start my session, but I then have to type :m +Main to bring the Main module into scope. Is there a command-line switch to control which modules are initially in scope with ghci? Thanks, Paul

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Re: [Haskell-cafe] Referential Transparency and Monads
by Luke Palmer 09 Apr '09

09 Apr '09

2009/4/9 Mark Spezzano <mark.spezzano(a)chariot.net.au> > Or does RT ignore the encapsulated data and just view the “action” > performed by the monad as the “value” of the monad? > If I understand you right, this is more-or-less correct. You may as well think of IO as some sort of algebraic type that you are building and returning. A value of type "IO Integer" is not, itself, an integer. Thus: main = let r = print "hello" in return () Prints nothing. RT steps in in a similar scenario: main = let r = print "hello" in do { r; r } Replacing "r" with its definition: main = do { print "hello"; print "hello" } As expected. Luke > > Just curious as to the rationale behind referential transparency and how it > applies to monads. > > > > Cheers, > > > > Mark Spezzano > > > > No virus found in this outgoing message. > Checked by AVG. > Version: 7.5.557 / Virus Database: 270.11.48/2048 - Release Date: 8/04/2009 > 7:02 PM > > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe(a)haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe > >

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Re: [Haskell-cafe] Referential Transparency and Monads
by Paul Keir 09 Apr '09

09 Apr '09

I think this topic is covered in Andrew Gordon's dissertation/book: Functional programming and input/output by Andrew D. Gordon You can read it online. Cheers, Paul

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Referential Transparency and Monads
by Mark Spezzano 09 Apr '09

09 Apr '09

Hi, How exactly do monads “solve” the problem of referential transparency? I understand RT to be such that a function can be replaced with a actual value. Since a monad could potentially encapsulate any other value—say, data read from a keyboard—doesn’t that violate the assumption of RT on monads? Or does RT ignore the encapsulated data and just view the “action” performed by the monad as the “value” of the monad? Just curious as to the rationale behind referential transparency and how it applies to monads. Cheers, Mark Spezzano No virus found in this outgoing message. Checked by AVG. Version: 7.5.557 / Virus Database: 270.11.48/2048 - Release Date: 8/04/2009 7:02 PM

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Problems getting errors with HXT
by rodrigo.bonifacio 09 Apr '09

09 Apr '09

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Debugging compile times (Template Haskell)
by Henning Günther 09 Apr '09

09 Apr '09

Hi, as the author of the encoding package[1] I'm quite annoyed by the extreeme long time it takes to compile a certain module (JISX0208). This module uses template haskell to generate both a Map (Map Char (Word8,Word8)) and an Array (UArray (Word8,Word8) Int) for character conversion. The file has about 6000 entries and the generated array has 8649 entries. Generating the syntax for the array and map is very fast (under a second) but compiling the code seems to take forever. Is there any way to find out why that is the case? I've tried pinpointing the problem but couldn't... [1] http://hackage.haskell.org/cgi-bin/hackage-scripts/package/encoding

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OFX libs available ?
by Simon Michael 09 Apr '09

09 Apr '09

Has anyone got code for OFX financial data handling they could share ? Best - Simon

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ANN: tree-monad 0.2
by Sebastian Fischer 08 Apr '09

08 Apr '09

I am pleased to announce version 0.2 of the package tree-monad that provides instances of MonadPlus that represent the search space of non- deterministic computations as a tree. In version 0.2 I have implemented an optimized CPS version of the tree monad based on the idea described in "Asymptotic Improvement of Computations over Free Monads" [^1]. The package is on Hackage: http://hackage.haskell.org/cgi-bin/hackage-scripts/package/tree-monad The sources are on Github: http://github.com/sebfisch/tree-monad Installation and usage instructions are at: http://sebfisch.github.com/tree-monad A possible application of search trees is parallel search as described in the blog post: http://www-ps.informatik.uni-kiel.de/~sebf/haskell/speedup-search-with-para… The package parallel-tree-search by Fabian Reck and myself http://hackage.haskell.org/cgi-bin/hackage-scripts/package/parallel-tree-se… implements the search described in the above blog post based on the hereby announced package tree-monad. Cheers, Sebastian [^1]: http://wwwtcs.inf.tu-dresden.de/~voigt/mpc08.pdf

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