May 2013 - Haskell-Cafe

lifted-base linking failure with GHC HEAD
by Mateusz Kowalczyk 31 May '13

31 May '13

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Greetings, I'm attempting to build lifted-base (as a dependency for ghc-mod) but cabal-install fails every time during the linking phase. I pasted the full log of `cabal install lifted-base --verbose' to hpaste at [1]. I'm attempting to build it with GHC HEAD. Now, I should note that I have different directories for each ghc version in my ~. So, for ghc 7.6.3 I would have ~/ghc-7.6.3 with appropriate bin, lib etc. in there. I thought that might have made `ld' confused but I just tried to `cabal install lifted-base' with 7.6.3 and it succeeded. Any ideas about what might be wrong? [1] - http://hpaste.org/89046 - -- Mateusz K. -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.19 (GNU/Linux) iQIcBAEBAgAGBQJRqTOjAAoJEM1mucMq2pqXt+QQALM9oWexq5NrWwOmcIj+m+08 DdNpj37KYx+M+3SUZYQ7RVyW7pf7ounsl/1OtGGndhGBeBpeamOMeZxaYvIZr7da IUjd3Vgnl0W44G+T9Wg64g+MIgyy75oLFPNnP0BGbcLzDk5wVgAl/xl+H193lLmu LbBJGAzAE+YHIx1mM+mNGsYgr80dhpGTs5jGdauAEdsnZFdFGj86sxBeFBeKVF78 md0PA1HDwJSVo2FyAAULWhgPDpwBrScjNjTU2etMpegMto1aDaV7rwvJeNeewv15 89o19tpWTvdwxtddOI6YlBKFTL0u80IBlCRQ+NWwu7PB35wR67MbOchXx4qGJSOt TxNelfW+C3h0BW7KLskQjqcEPUKD1hYB5lAnOH2VOaTSFEN9QN66GhC3BHLJCBiu UWZBRyUikAsjRvWL6eQI+vc8fnPSieNa5K2jdPe410uHojr7Eq28WCCXsejaQ3e+ TviDUWLmGfJk97Zmz2NPy4oGqwNYvOQqXKZ4GIpzD1/UHfNUw9wykPuDCapuvXPl OcSlSyjPk70jG32aLEalVZKPYZ1g15VSY6d6WYquZO0mGpwL15Gvc8V7SlZfNpvT 8maX5CQEeNXqfEbl2PwnkfoCwvW7x2p7uD+M2MHxOozkn5vtUonXqFCOVCftE/nL KsYrafRMuMzNRCn4kE/M =OCEQ -----END PGP SIGNATURE-----

1 0

Performance difference between Linux and Windows?
by James Jones 31 May '13

31 May '13

I've been having a great deal of fun writing a program to solve this year's Code Jam "Fair and Square"problem in Haskell (and learning about Haskell in the process). Having gotten it to work, I've been optimizing it as best I can. I'm not quite in Captain Ahab mode, but before I let it go I would like to find out what's behind a difference I've seen compiling and running the program under Linux and under Windows 7. Profiling it under Linux (compiled with GHC 7.4.1), it had a total allocation of 165,375,112 bytes. I had an opportunity to compile and run on Windows 7, with GHC 7.4.2. I expected it to run faster, since the Windows computer had a 3.1 GHz i7 and my Linux computer has a 2.8 GHz AMD Propus, but what I didn't expect was that the total allocation on the Windows version was 88,438,372 bytes! Thinking it might be due to a compiler improvement, I upgraded my Linux computer to Ubuntu 13.04 so I could get a newer GHC, but it didn't make much difference: total allocation 163,248,688 bytes. So, I'm wondering: what is it about either the Windows implementation or GHC 7.4.2 in particular that would make a factor of two difference in memory allocation? Should anyone wish to compile the program, let me know the best way to make the source available and I will happily do so; I also use Twan van Laarhoven's semilattice search tree code available at http://twanvl.nl/blog/haskell/SemilatticeSearchTree. James Jones

2 1

Job opening Ph D student in type error diagnosis for domain specific languages in Haskell
by Jurriaan Hage 31 May '13

31 May '13

Dear Haskellers, Apologies in case you have received multiple copies. best, Jur =============================================================================== VACANCY : 1x Phd Student in domain specific type error diagnosis for Haskell =============================================================================== The activities of the Software Systems division at Utrecht University include research on programming methodologies, compiler construction, and program analysis, validation, and verification. For information about the research group of Software Technology, see: http://www.cs.uu.nl/wiki/Center Financed by the Netherlands Organisation for Scientific Research (NWO), we currently have a job opening for: * 1x PhD researcher (Ph D student) Software Technology Domain-specific languages (DSLs) have the potential both to reduce the effort of programming, and to result in programs that are easier to understand and maintain. For various good reasons, researchers have proposed to embed DSLs (then called EDSLs) into a general purpose host language. An important disadvantage of such an embedding is that it is very hard to make type error diagnosis domain-aware, because inconsistencies are by default explained in terms of the host language. We are currently looking for a highly motivated Ph D student to investigate this problem in the context of the functional language Haskell. The basic approach is to scale the concept of specialized type rules as developed by (Heeren, Hage and Swierstra, ICFP '03, see link below) for Haskell '98 to modern day Haskell with all of its type system extensions. The work is both technically challenging, i.e., how do you ensure that modifications to the type diagnositic process do not inadvertently change the type system, and practically immediately useful: making domain-specific type error diagnosis a reality for a full sized language such as Haskell is likely to have a pervasive influence on the field of domain-specific languages, and the language Haskell. The ICFP '03 paper can be found at http://www.cs.uu.nl/people/jur/scriptingthetypeinferencer.pdf A project paper that describes the context and aims of the current project can be found here: http://www.cs.uu.nl/people/jur/tfp2013_submission_2.pdf At first, the work will be prototyped in our own Utrecht Haskell Compiler. If succesfull, the work will also make its way into the GHC. We expect the candidate to communicate the results academically, to present the work at scientific conferences, to supervise Master students, and to assist in teaching courses at Bachelor or Master level. --------------------------------- What we are looking for --------------------------------- The candidate should have an MSc in Computer Science, be highly motivated, speak and write English very well, and be proficient in producing scientific reports. Knowledge of and experience with at least one of the following two areas is essential: * functional programming, and Haskell in particular * type system concepts Furthermore, we expect the candidate to be able to reason formally. Experience in compiler construction is expected to be useful in this project. --------------------------------- What we offer --------------------------------- You are offered a full-time position for 4 years. The gross salary is in the range between € 2083,- and maximum € 2664,- per month. The salary is supplemented with a holiday bonus of 8% and an end-of-year bonus of 8,3% per year. In addition we offer: a pension scheme, a partially paid parental leave, flexible employment conditions. Conditions are based on the Collective Labour Agreement Dutch Universities. We aim to start November 1, 2013 at the latest, but preferably sooner. --------------------------------- In order to apply --------------------------------- To apply please attach a letter of motivation, a curriculum vitae, and (email) addresses of two referees. Make sure to also include a transcript of the courses you have followed (at bachelor and master level), with the grades you obtained, and to include a sample of your scientific writing, e.g., the pdf of your master thesis. It is possible to apply for this position if you are close to obtaining your Master's. In that case include a letter of your supervisor with an estimate of your progress, and do not forget to include at least a sample of your technical writing skills. Application closes on the 20th of June 2013. For application, visit http://www.cs.uu.nl/vacatures/en/583630.html and follow the link to the official job application page at the bottom. --------------- Contact person --------------- For further information you can direct your inquiries to: Dr. Jurriaan Hage Phone: (+31) 30 253 3283 e-mail: J.Hage(a)uu.nl. website: http://www.cs.uu.nl/wiki/Hage/WebHome

1 0

Call for Papers IFL 2013
by publicityifl＠gmail.com 31 May '13

31 May '13

=============================================================================== VACANCY : 1x Phd Student in domain specific type error diagnosis for Haskell =============================================================================== The activities of the Software Systems division at Utrecht University include research on programming methodologies, compiler construction, and program analysis, validation, and verification. For information about the research group of Software Technology, see: http://www.cs.uu.nl/wiki/Center Financed by the Netherlands Organisation for Scientific Research (NWO), we currently have a job opening for: * 1x PhD researcher (Ph D student) Software Technology Domain-specific languages (DSLs) have the potential both to reduce the effort of programming, and to result in programs that are easier to understand and maintain. For various good reasons, researchers have proposed to embed DSLs (then called EDSLs) into a general purpose host language. An important disadvantage of such an embedding is that it is very hard to make type error diagnosis domain-aware, because inconsistencies are by default explained in terms of the host language. We are currently looking for a highly motivated Ph D student to investigate this problem in the context of the functional language Haskell. The basic approach is to scale the concept of specialized type rules as developed by (Heeren, Hage and Swierstra, ICFP '03, see link below) for Haskell '98 to modern day Haskell with all of its type system extensions. The work is both technically challenging, i.e., how do you ensure that modifications to the type diagnositic process do not inadvertently change the type system, and practically immediately useful: making domain-specific type error diagnosis a reality for a full sized language such as Haskell is likely to have a pervasive influence on the field of domain-specific languages, and the language Haskell. The ICFP '03 paper can be found at http://www.cs.uu.nl/people/jur/scriptingthetypeinferencer.pdf A project paper that describes the context and aims of the current project can be found here: http://www.cs.uu.nl/people/jur/tfp2013_submission_2.pdf At first, the work will be prototyped in our own Utrecht Haskell Compiler. If succesfull, the work will also make its way into the GHC. We expect the candidate to communicate the results academically, to present the work at scientific conferences, to supervise Master students, and to assist in teaching courses at Bachelor or Master level. --------------------------------- What we are looking for --------------------------------- The candidate should have an MSc in Computer Science, be highly motivated, speak and write English very well, and be proficient in producing scientific reports. Knowledge of and experience with at least one of the following two areas is essential: * functional programming, and Haskell in particular * type system concepts Furthermore, we expect the candidate to be able to reason formally. Experience in compiler construction is expected to be useful in this project. --------------------------------- What we offer --------------------------------- You are offered a full-time position for 4 years. The gross salary is in the range between Û 2083,- and maximum Û 2664,- per month. The salary is supplemented with a holiday bonus of 8% and an end-of-year bonus of 8,3% per year. In addition we offer: a pension scheme, a partially paid parental leave, flexible employment conditions. Conditions are based on the Collective Labour Agreement Dutch Universities. We aim to start November 1, 2013 at the latest, but preferably sooner. --------------------------------- In order to apply --------------------------------- To apply please attach a letter of motivation, a curriculum vitae, and (email) addresses of two referees. Make sure to also include a transcript of the courses you have followed (at bachelor and master level), with the grades you obtained, and to include a sample of your scientific writing, e.g., the pdf of your master thesis. It is possible to apply for this position if you are close to obtaining your Master's. In that case include a letter of your supervisor with an estimate of your progress, and do not forget to include at least a sample of your technical writing skills. Application closes on the 20th of June 2013. For application, visit http://www.cs.uu.nl/vacatures/en/583630.html and follow the link to the official job application page at the bottom. --------------- Contact person --------------- For further information you can direct your inquiries to: Dr. Jurriaan Hage Phone: (+31) 30 253 3283 e-mail: J.Hage(a)uu.nl. website: http://www.cs.uu.nl/wiki/Hage/WebHome

2 1

Projects using Shake
by Frerich Raabe 31 May '13

31 May '13

Hi, I'm considering to convert one of my projects to Shake; everything I've seen so far seemed really interesting! However, before I start, I'd like to see how other people structure their Shake-based build systems. I tried to find some open source projects which showcase how Shake is used, but unfortunately I didn't find anything yet. Is anybody aware of open source projects which I could look at, or is there maybe a conventional file extension for… what do you call them, "Shakefiles"? other than .hs which I could google for? -- Frerich Raabe - raabe(a)froglogic.com www.froglogic.com - Multi-Platform GUI Testing

3 2

Haskell Weekly News: Issue 268
by Daniel Santa Cruz 30 May '13

30 May '13

Welcome to issue 268 of the HWN, an issue covering crowd-sourced bits of information about Haskell from around the web. This issue covers the week of May 12 to 25, 2013. Quotes of the Week * tikhonjelvis: the lesson is that the fix function exists to "fix" any type problems you may encounter * shachaf: The trouble with peano arithmetic is that it stops at 88. * Peaker: Python's dynamic nature adds slowness and unsafety, but doesn't actually make things more expressive * sj4nz: Programming in weakly-typed languages forever after will feel like working with punch cards. Send in your program to the nodejs interpreter and hope for a result to come back. * xplat: if you want to carry your machete all the time and not make people nervous, you need to constantly blaze trails * otters: heh, F# is just the unboxed version of F * quchen: This was the first time in months that I thought imperatively. Conclusion: 1. it complicated things, 2. it was refreshing * cmccann: I still kind of expect that the next standard will be haskell2017 or something, and all it will do is a minor change to lexical syntax of comments that fixes nothing but nevertheless breaks 20% of hackage. * cmccann: [on reimplementing cryptography in pure Haskell] writing in Haskell lets you use type safety to ensure that all the security holes you create are subtle instead of obvious. Top Reddit Stories * Haskell in Production [slides] Domain: mth.io, Score: 60, Comments: 114 On Reddit: [1] http://goo.gl/ldnv0 Original: [2] http://goo.gl/tMjTd * B-trees with GADTs Domain: matthew.brecknell.net, Score: 56, Comments: 6 On Reddit: [3] http://goo.gl/Sjf9U Original: [4] http://goo.gl/sQnYW * Yearly revisions to the Haskell language: who killed Haskell Prime? Domain: self.haskell, Score: 54, Comments: 19 On Reddit: [5] http://goo.gl/5GWKg Original: [6] http://goo.gl/5GWKg * Elm paper accepted at PLDI: Asynchronous FRP for GUIs! Domain: people.seas.harvard.edu, Score: 51, Comments: 4 On Reddit: [7] http://goo.gl/iYiyh Original: [8] http://goo.gl/98jft * The complete correctness of sorting [Agda] Domain: twanvl.nl, Score: 49, Comments: 5 On Reddit: [9] http://goo.gl/PLH6m Original: [10] http://goo.gl/RQGZn * Anatomy of an MVar operation Domain: blog.ezyang.com, Score: 47, Comments: 7 On Reddit: [11] http://goo.gl/7miao Original: [12] http://goo.gl/3ZHSI * Typing Haskell in Haskell Domain: web.cecs.pdx.edu, Score: 44, Comments: 34 On Reddit: [13] http://goo.gl/q1ghy Original: [14] http://goo.gl/M5csQ * STM in Haskell is better because of types Domain: joeyh.name, Score: 44, Comments: 8 On Reddit: [15] http://goo.gl/wj9Ab Original: [16] http://goo.gl/fmLM1 * Typed Template Haskell ready for testing in GHC Domain: haskell.org, Score: 44, Comments: 13 On Reddit: [17] http://goo.gl/he61y Original: [18] http://goo.gl/YJIZB * A detailed look at GHC's STM implementation from a non-GHC hacker Domain: fryguybob.github.io, Score: 38, Comments: 11 On Reddit: [19] http://goo.gl/pTp2c Original: [20] http://goo.gl/4oe3Y * New Haskell Communities and Activity Report (May 2013) is out Domain: haskell.org, Score: 37, Comments: 2 On Reddit: [21] http://goo.gl/P2kz1 Original: [22] http://goo.gl/YoIE4 * Three examples of problems with Lazy I/O Domain: newartisans.com, Score: 36, Comments: 31 On Reddit: [23] http://goo.gl/reKqZ Original: [24] http://goo.gl/ZagPt * Understanding the Yoneda Lemma Domain: fpcomplete.com, Score: 35, Comments: 48 On Reddit: [25] http://goo.gl/RUZ4h Original: [26] http://goo.gl/xbAJj * Simon Peyton Jones to keynote Haskell eXchange 2013! Domain: skillsmatter.com, Score: 35, Comments: 2 On Reddit: [27] http://goo.gl/DlfRt Original: [28] http://goo.gl/5lpwh * Greg Hale's "Functional programming elevator pitch" Domain: fpcomplete.com, Score: 34, Comments: 8 On Reddit: [29] http://goo.gl/gbhX3 Original: [30] http://goo.gl/QrrxP * FP Complete is looking for a Technical Sales Engineer and Support Specialist Domain: fpcomplete.com, Score: 32, Comments: 1 On Reddit: [31] http://goo.gl/nYNci Original: [32] http://goo.gl/VGCoa * A Typed Markup Language Based On Haskell Domain: blog.functorial.com, Score: 31, Comments: 9 On Reddit: [33] http://goo.gl/eLLjV Original: [34] http://goo.gl/wFxcv * Announcing: Snap Framework v0.12 Domain: snapframework.com, Score: 28, Comments: 2 On Reddit: [35] http://goo.gl/5wYLk Original: [36] http://goo.gl/KibyP * John Wiegley's "Understanding Continuations", on School of Haskell Domain: fpcomplete.com, Score: 27, Comments: 17 On Reddit: [37] http://goo.gl/ZT7d6 Original: [38] http://goo.gl/YitVR Top StackOverflow Questions * Why are if expressions frowned upon in Haskell? votes: 20, answers: 6 Read on SO: [39] http://goo.gl/NejhX * Haskell: `Map (a,b) c` versus `Map a (Map b c)`? votes: 19, answers: 3 Read on SO: [40] http://goo.gl/8f1hf * Why recursive `let` make space effcient? votes: 18, answers: 3 Read on SO: [41] http://goo.gl/QTLYQ * Should do-notation be avoided in Haskell? [duplicate] votes: 16, answers: 7 Read on SO: [42] http://goo.gl/MGiFr * Correspondence between type classes and grammar levels in the Chomsky hierarchy votes: 15, answers: 1 Read on SO: [43] http://goo.gl/LRJy2 * Calling Haskell from C# votes: 14, answers: 2 Read on SO: [44] http://goo.gl/n9QB1 * How do exceptions work in Haskell (part two)? votes: 13, answers: 1 Read on SO: [45] http://goo.gl/U2GDR * Can a monad be a comonad? votes: 11, answers: 5 Read on SO: [46] http://goo.gl/ESrc2 * Dynamic Programming Memoization in Haskell votes: 11, answers: 1 Read on SO: [47] http://goo.gl/Gp7c8 * Employing arrows to fold a list of tuples votes: 11, answers: 1 Read on SO: [48] http://goo.gl/shRWV Until next time, +Daniel Santa Cruz References 1. http://mth.io/talks/haskell-in-production/ 2. http://www.reddit.com/r/haskell/comments/1etssw/haskell_in_production_slide… 3. http://matthew.brecknell.net/post/btree-gadt/ 4. http://www.reddit.com/r/haskell/comments/1efuog/btrees_with_gadts/ 5. http://www.reddit.com/r/haskell/comments/1esmhj/yearly_revisions_to_the_has… 6. http://www.reddit.com/r/haskell/comments/1esmhj/yearly_revisions_to_the_has… 7. http://people.seas.harvard.edu/~chong/pubs/pldi13-elm.pdf 8. http://www.reddit.com/r/haskell/comments/1eie6m/elm_paper_accepted_at_pldi_… 9. http://twanvl.nl/blog/agda/sorting 10. http://www.reddit.com/r/haskell/comments/1exv2t/the_complete_correctness_of… 11. http://blog.ezyang.com/2013/05/anatomy-of-an-mvar-operation/ 12. http://www.reddit.com/r/haskell/comments/1eostu/anatomy_of_an_mvar_operatio… 13. http://web.cecs.pdx.edu/~mpj/thih/TypingHaskellInHaskell.html 14. http://www.reddit.com/r/haskell/comments/1e6s68/typing_haskell_in_haskell/ 15. http://joeyh.name/blog/entry/the_newinwheezy_game:_STM/ 16. http://www.reddit.com/r/haskell/comments/1e8ow9/stm_in_haskell_is_better_be… 17. http://www.haskell.org/pipermail/ghc-devs/2013-May/001255.html 18. http://www.reddit.com/r/haskell/comments/1egfra/typed_template_haskell_read… 19. http://fryguybob.github.io/STM-Commentary/ 20. http://www.reddit.com/r/haskell/comments/1ejgjo/a_detailed_look_at_ghcs_stm… 21. http://haskell.org/communities/05-2013/html/report.html 22. http://www.reddit.com/r/haskell/comments/1e601k/new_haskell_communities_and… 23. http://newartisans.com/2013/05/three-examples-of-problems-with-lazy-io 24. http://www.reddit.com/r/haskell/comments/1e8k3k/three_examples_of_problems_… 25. https://www.fpcomplete.com/user/bartosz/understanding-yoneda 26. http://www.reddit.com/r/haskell/comments/1eelao/understanding_the_yoneda_le… 27. http://skillsmatter.com/event/scala/haskell-exchange/te-7391 28. http://www.reddit.com/r/haskell/comments/1ewq54/simon_peyton_jones_to_keyno… 29. https://www.fpcomplete.com/user/imalsogreg/functional-programming-elevator-… 30. http://www.reddit.com/r/haskell/comments/1ewvhm/greg_hales_functional_progr… 31. https://www.fpcomplete.com/page/product_specialist 32. http://www.reddit.com/r/haskell/comments/1ezeng/fp_complete_is_looking_for_… 33. http://blog.functorial.com/posts/2013-05-18-Typed-Markup-Language.html 34. http://www.reddit.com/r/haskell/comments/1elhj2/a_typed_markup_language_bas… 35. http://snapframework.com/blog/2013/05/15/snap-0.12-released 36. http://www.reddit.com/r/haskell/comments/1ef3kt/announcing_snap_framework_v… 37. https://www.fpcomplete.com/user/jwiegley/understanding-continuations 38. http://www.reddit.com/r/haskell/comments/1e977w/john_wiegleys_understanding… 39. http://stackoverflow.com/questions/16572446/why-are-if-expressions-frowned-… 40. http://stackoverflow.com/questions/16613032/haskell-map-a-b-c-versus-map-a-… 41. http://stackoverflow.com/questions/16632143/why-recursive-let-make-space-ef… 42. http://stackoverflow.com/questions/16726659/should-do-notation-be-avoided-i… 43. http://stackoverflow.com/questions/16607637/correspondence-between-type-cla… 44. http://stackoverflow.com/questions/16615641/calling-haskell-from-c-sharp 45. http://stackoverflow.com/questions/16678165/how-do-exceptions-work-in-haske… 46. http://stackoverflow.com/questions/16551734/can-a-monad-be-a-comonad 47. http://stackoverflow.com/questions/16585741/dynamic-programming-memoization… 48. http://stackoverflow.com/questions/16676758/employing-arrows-to-fold-a-list… 49. https://plus.google.com/105107667630152149014/about

1 0

Re: [Haskell-cafe] using a win32 dll (Happy too soon)
by Brandon Allbery 30 May '13

30 May '13

On Thu, May 30, 2013 at 3:15 AM, Kees Bleijenberg < k.bleijenberg(a)lijbrandt.nl> wrote: > argument. The dll is in the PATH. I don't understand why it needs the -L > argument. I'll figure this out later. If I use -lglasPng.dll (additional > .dll) it doesn't work either. > Unix has standard places to install and search for libraries; Windows doesn't, and almost every library that doesn't come with your build system will need at least one -L option to tell the linker where to find it. As I mentioned in my first message, it looks for multiple file names with -l: first it tries a .dll, then it tries a .lib (static library or import library for older DLLs). It does this mechanically; if you also include the .dll suffix, then it looks for library.dll.dll and library.dll.lib, which is almost certainly wrong. -- brandon s allbery kf8nh sine nomine associates allbery.b(a)gmail.com ballbery(a)sinenomine.net unix, openafs, kerberos, infrastructure, xmonad http://sinenomine.net

3 2

Re: [Haskell-cafe] [haskell.org Google Summer of Code 2013] Approved Projects
by Stephen Tetley 30 May '13

30 May '13

Similarly (to some degree), in the ML world John Reppy had a very nice system that employed user customization via combinators rather than inference to generate application/library specific FFIs, see: http://people.cs.uchicago.edu/~jhr/papers/2006/gpce-fig.pdf On 29 May 2013 18:57, Jason Dagit <dagitj(a)gmail.com> wrote: > Are you folks aware of the work on this topic by Tristan Ravitch? > https://github.com/travitch/foreign-inference > > Jason > > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe(a)haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe

2 1

ANN stm-chans 2.1 / 3.0
by wren ng thornton 30 May '13

30 May '13

-------------------------------------------- -- stm-chans 2.1 / 3.0 -------------------------------------------- The stm-chans package offers a collection of channel types, similar to Control.Concurrent.STM.{TChan,TQueue} but with additional features. -------------------------------------------- -- Changes (since 2.0.0) -------------------------------------------- By popular demand, the functions newBroadcastTMChan{,IO} have been added. However, these rely on newBroadcastTChan{,IO} which are only available in stm >= 2.4 and do not appear to be replicable using the public API of stm < 2.4. Thus, the minimum version of stm is now 2.4, which obviates all the compatibility modules. Version 2.1.0 adds the new functions and issues deprecation warnings about using the compatibility modules. This version is just to help people transition. If you can use this version without warnings (i.e., you don't use the Compat modules directly) then you should be able to use version 3.0 as well. Version 3.0 removes the compatibility modules. -------------------------------------------- -- Long description -------------------------------------------- In particular stm-chans offers the following data types: * Control.Concurrent.STM.TBChan: Bounded FIFO channels. When the channel is full, writers will block/retry. This ensures that the writers do not get too far ahead of the readers, which helps to make sure that memory and cpu resources are used responsibly. * Control.Concurrent.STM.TMChan: Closeable FIFO channels. * Control.Concurrent.STM.TMQueue: Closeable FIFO queues. Like TChan (Maybe a) but with a monotonicity guarantee that once Nothing is returned all future reads will be Nothing as well. * Control.Concurrent.STM.TBMChan: Bounded Closeable FIFO channels. * Control.Concurrent.STM.TBMQueue: Bounded Closeable FIFO queues. Combines the capabilities of TBChan and TMChan. -------------------------------------------- -- Links -------------------------------------------- Homepage: http://code.haskell.org/~wren/ Hackage: http://hackage.haskell.org/package/stm-chans Darcs: http://community.haskell.org/~wren/stm-chans Haddock (Darcs version): http://community.haskell.org/~wren/stm-chans/dist/doc/html/stm-chans -- Live well, ~wren

1 0

Re: [Haskell-cafe] using a win32 dll (Happy too soon)
by Brandon Allbery 30 May '13

30 May '13

On Thu, May 30, 2013 at 11:46 AM, Kees Bleijenberg < k.bleijenberg(a)lijbrandt.nl> wrote: > Brandon, thanks again for your explanation > Are you sure about the non existing search order for dynamic loaded dll’s? > I.e. > http://msdn.microsoft.com/en-us/library/windows/desktop/ms682586(v=vs.85).a… there is a search order, starting with the current directory (I think). > There is a search order. What I said is that there are no standard locations to install things. That is, every library package stows stuff in its own directory structure and no compiler can possibly know all the places it needs to look to find every library off in its own directory. > I don’t understand why the linker needs to see the dll anyway. Because it's better to catch "that symbol doesn't exist" at build time instead of throwing an ugly error at runtime, among other things. > possible in Delphi. Is Haskell dynamic loading more limited? > There are ways to do that kind of dynamic linking; this is not one of them. C and C++ don't automatically dynload the way you're thinking either, because you should test for the DLL you're distributing (you are distributing it, right, not forcing the end user on a wild goose chase to find their own copy of the DLL, hoping it's the right/compatible version, and figure out where to put it so your program will run?) being the right one *when you build the program*, not defer that test until it is run. If you think about it, this is very similar to doing your type checking at compile time instead of runtime. If you want lazy type checking, why are you using Haskell? If you want lazy library checking, why are you using a compiler? -- brandon s allbery kf8nh sine nomine associates allbery.b(a)gmail.com ballbery(a)sinenomine.net unix, openafs, kerberos, infrastructure, xmonad http://sinenomine.net

1 0