November 2008 - Haskell-Cafe

Re: [Haskell-cafe] Calling Haskell from other languages?
by Donn Cave 11 Nov '08

11 Nov '08

Quoth Colin Paul Adams <colin(a)colina.demon.co.uk>: | Is there a way to call Haskell code from other languages? I have looked on | the wiki, and as far as I can see, it only talks about the other way | round (when Haskell is the main program). There sure is a way to call from other languages - cf. "foreign export" - but don't know how hard it would be to make Haskell live without its "main", which performs a lot of runtime initialization. For me (with nhc98) it's a lot easier to use a Haskell "main" that's just a brief wrapper: module Main (main) where import NHC.FFI foreign import ccall "cmain" cmain :: IO () main = cmain (... where "cmain" is an external entry point in the C code, which can then call Haskell as required.) Donn

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announce: Workflow-0.1
by Alberto G. Corona 11 Nov '08

11 Nov '08

I needed to to define multiuser web workflows in the most transparent way. I wondered if a state monad could transparently bring automatic checkpointing of each action and automatic resume after failure. In this way a long living computation could be expressed in a single monadic computation. Additionally, for inter process communications, this package includes a primitive for activating a workflow whenever any action result meet certain condition. There are also primitives for start/restart processes, retrieval of intermediate results and unsafe IO actions inside the state monad... http://hackage.haskell.org/cgi-bin/hackage-scripts/package/Workflow Cabal description: Transparent low level support (state logging, resume of the computation, wait for data condition) for long living, event driven processes. Workflow give the two first services to any monadic computation of type (a-> m a) usually m=IO f x >>=\x'-> g x' >>= \x''->... z by prefixing the user with the method "step": step f x >>= \x'-> step g x' >>= \x''->... This means that a workflow can be described with the familiar "do" notation. In principle, there is no other limitation on the syntax but the restriction (a -> m a): All computations consume and produce the same type of data. do notation is supported fully. Workflow export a few primitives that bring the following services: - transparent checkpointing of each step in permanent storage using TCache (step) - resume of the monadic computation at the last checkpoint after soft or hard interruption - use of versioning techniques for storing object changes (using RefSerialize) - retrieval of the object at any previous step - suspend the computation (waitFor) until the input object meet certain conditions. useful for inter-workflow comunications. At the end of the workflow all the intermediate data is erased. see demos and the header of Control.TCache for documentation. This is a piece of code is a loop that imput numbers (demo.hs). there is another process, that check the numbers entered and return Finish when match the desired number. that is detected by this thread and finalize. When number of tries are 9, The process finish, this is detected by the other process and finalizes also. That ilustrates the use of event handling (waitFor) and step execution. askNumbers name d = do step2 $ threadDelay 5000 -- wait for the other tread to process. r <- step (waitFor anything) d -- get the last value of the object with key "try-finish", to look for the other thread actions case r of Finish msg -> step2 $ print msg --the other thread sent a finalize response Try 9 num -> step1 $ return $ Finish "sorry, no more guesses" --send finalization to the wait thread _ -> do nd <- step (askNumber name) d askNumbers name nd where anything= \_-> True

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GHC 6.10 / Mac OS X / Library problem
by Pieter Laeremans 11 Nov '08

11 Nov '08

Hello, I've got a problem when I want to install pcre-light on OS X, with the latest version of GHC (binary package from haskell.org) It is not clear to me which flags to pass to ghc, to tell it to look at /opt/local/include for the pcre-light.h header. Any suggestions ? thanks, Pieter :cabal-install-0.6.0 pieter$ sudo cabal install pcre-light Password: Resolving dependencies... 'pcre-light-0.3.1' is cached. Configuring pcre-light-0.3.1... Preprocessing library pcre-light-0.3.1... Base.hsc:103:18: error: pcre.h: No such file or directory Base.hsc: In function 'main': Base.hsc:401: error: 'PCRE_ANCHORED' undeclared (first use in this function) Base.hsc:401: error: (Each undeclared identifier is reported only once Base.hsc:401: error: for each function it appears in.) Base.hsc:404: error: 'PCRE_AUTO_CALLOUT' undeclared (first use in this function) Base.hsc:407: error: 'PCRE_CASELESS' undeclared (first use in this function) Base.hsc:410: error: 'PCRE_DOLLAR_ENDONLY' undeclared (first use in this function) Base.hsc:413: error: 'PCRE_DOTALL' undeclared (first use in this function) Base.hsc:416: error: 'PCRE_DUPNAMES' undeclared (first use in this function) Base.hsc:419: error: 'PCRE_EXTENDED' undeclared (first use in this function) Base.hsc:422: error: 'PCRE_EXTRA' undeclared (first use in this function) Base.hsc:425: error: 'PCRE_FIRSTLINE' undeclared (first use in this function) Base.hsc:428: error: 'PCRE_MULTILINE' undeclared (first use in this function) Base.hsc:431: error: 'PCRE_NEWLINE_CR' undeclared (first use in this function) Base.hsc:434: error: 'PCRE_NEWLINE_CRLF' undeclared (first use in this function) Base.hsc:437: error: 'PCRE_NEWLINE_LF' undeclared (first use in this function) Base.hsc:440: error: 'PCRE_NO_AUTO_CAPTURE' undeclared (first use in this function) Base.hsc:443: error: 'PCRE_UNGREEDY' undeclared (first use in this function) Base.hsc:446: error: 'PCRE_UTF8' undeclared (first use in this function) Base.hsc:449: error: 'PCRE_NO_UTF8_CHECK' undeclared (first use in this function) Base.hsc:621: error: 'PCRE_NOTBOL' undeclared (first use in this function) Base.hsc:624: error: 'PCRE_NOTEOL' undeclared (first use in this function) Base.hsc:627: error: 'PCRE_NOTEMPTY' undeclared (first use in this function) Base.hsc:633: error: 'PCRE_PARTIAL' undeclared (first use in this function) Base.hsc:631: error: 'PCRE_ERROR_NOMATCH' undeclared (first use in this function) Base.hsc:634: error: 'PCRE_ERROR_NULL' undeclared (first use in this function) Base.hsc:637: error: 'PCRE_ERROR_BADOPTION' undeclared (first use in this function) Base.hsc:640: error: 'PCRE_ERROR_BADMAGIC' undeclared (first use in this function) Base.hsc:643: error: 'PCRE_ERROR_UNKNOWN_NODE' undeclared (first use in this function) Base.hsc:646: error: 'PCRE_ERROR_NOMEMORY' undeclared (first use in this function) Base.hsc:649: error: 'PCRE_ERROR_NOSUBSTRING' undeclared (first use in this function) Base.hsc:652: error: 'PCRE_ERROR_MATCHLIMIT' undeclared (first use in this function) Base.hsc:655: error: 'PCRE_ERROR_CALLOUT' undeclared (first use in this function) Base.hsc:658: error: 'PCRE_ERROR_BADUTF8' undeclared (first use in this function) Base.hsc:661: error: 'PCRE_ERROR_BADUTF8_OFFSET' undeclared (first use in this function) Base.hsc:664: error: 'PCRE_ERROR_PARTIAL' undeclared (first use in this function) Base.hsc:667: error: 'PCRE_ERROR_BADPARTIAL' undeclared (first use in this function) Base.hsc:670: error: 'PCRE_ERROR_INTERNAL' undeclared (first use in this function) Base.hsc:673: error: 'PCRE_ERROR_BADCOUNT' undeclared (first use in this function) Base.hsc:676: error: 'PCRE_ERROR_DFA_UITEM' undeclared (first use in this function) Base.hsc:679: error: 'PCRE_ERROR_DFA_UCOND' undeclared (first use in this function) Base.hsc:682: error: 'PCRE_ERROR_DFA_UMLIMIT' undeclared (first use in this function) Base.hsc:685: error: 'PCRE_ERROR_DFA_WSSIZE' undeclared (first use in this function) Base.hsc:688: error: 'PCRE_ERROR_DFA_RECURSE' undeclared (first use in this function) Base.hsc:691: error: 'PCRE_ERROR_RECURSIONLIMIT' undeclared (first use in this function) Base.hsc:665: error: 'PCRE_INFO_OPTIONS' undeclared (first use in this function) Base.hsc:668: error: 'PCRE_INFO_SIZE' undeclared (first use in this function) Base.hsc:671: error: 'PCRE_INFO_CAPTURECOUNT' undeclared (first use in this function) Base.hsc:674: error: 'PCRE_INFO_BACKREFMAX' undeclared (first use in this function) Base.hsc:677: error: 'PCRE_INFO_FIRSTBYTE' undeclared (first use in this function) Base.hsc:680: error: 'PCRE_INFO_FIRSTCHAR' undeclared (first use in this function) Base.hsc:683: error: 'PCRE_INFO_FIRSTTABLE' undeclared (first use in this function) Base.hsc:686: error: 'PCRE_INFO_LASTLITERAL' undeclared (first use in this function) Base.hsc:689: error: 'PCRE_INFO_NAMEENTRYSIZE' undeclared (first use in this function) Base.hsc:692: error: 'PCRE_INFO_NAMECOUNT' undeclared (first use in this function) Base.hsc:695: error: 'PCRE_INFO_NAMETABLE' undeclared (first use in this function) Base.hsc:698: error: 'PCRE_INFO_STUDYSIZE' undeclared (first use in this function) Base.hsc:701: error: 'PCRE_INFO_DEFAULT_TABLES' undeclared (first use in this function) Base.hsc:690: error: 'PCRE_CONFIG_UTF8' undeclared (first use in this function) Base.hsc:693: error: 'PCRE_CONFIG_NEWLINE' undeclared (first use in this function) Base.hsc:696: error: 'PCRE_CONFIG_LINK_SIZE' undeclared (first use in this function) Base.hsc:699: error: 'PCRE_CONFIG_POSIX_MALLOC_THRESHOLD' undeclared (first use in this function) Base.hsc:702: error: 'PCRE_CONFIG_MATCH_LIMIT' undeclared (first use in this function) Base.hsc:705: error: 'PCRE_CONFIG_STACKRECURSE' undeclared (first use in this function) Base.hsc:708: error: 'PCRE_CONFIG_UNICODE_PROPERTIES' undeclared (first use in this function) Base.hsc:711: error: 'PCRE_CONFIG_MATCH_LIMIT_RECURSION' undeclared (first use in this function) Base.hsc:724: error: 'PCRE_EXTRA_STUDY_DATA' undeclared (first use in this function) Base.hsc:727: error: 'PCRE_EXTRA_MATCH_LIMIT' undeclared (first use in this function) Base.hsc:730: error: 'PCRE_EXTRA_CALLOUT_DATA' undeclared (first use in this function) Base.hsc:733: error: 'PCRE_EXTRA_TABLES' undeclared (first use in this function) Base.hsc:736: error: 'PCRE_EXTRA_MATCH_LIMIT_RECURSION' undeclared (first use in this function) compiling dist/build/Text/Regex/PCRE/Light/Base_hsc_make.c failed command was: /usr/bin/gcc -c -D__GLASGOW_HASKELL__=610 -I/Library/Frameworks/GHC.framework/Versions/610/usr/lib/ghc-6.10.1/bytestring-0.9.1.4/include -I/Library/Frameworks/GHC.framework/Versions/610/usr/lib/ghc-6.10.1/base-4.0.0.0/include -I/Library/Frameworks/GHC.framework/Versions/610/usr/lib/ghc-6.10.1/include -IPAPI_INCLUDE_DIR dist/build/Text/Regex/PCRE/Light/Base_hsc_make.c -o dist/build/Text/Regex/PCRE/Light/Base_hsc_make.o cabal: Error: some packages failed to install: pcre-light-0.3.1 failed during the building phase. The exception was: exit: ExitFailure 1 -- Pieter Laeremans <pieter(a)laeremans.org> "The future is here. It's just not evenly distributed yet." W. Gibson

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Exporting a Type Class for Type Signatures
by Dominic Steinitz 11 Nov '08

11 Nov '08

In the crypto package, I have two functions > encrypt :: AESKey a => a -> Word128 -> Word128 > decrypt :: AESKey a => a -> Word128 -> Word128 which are exported. I also have > class (Bits a, Integral a) => AESKey a > > instance AESKey Word128 > instance AESKey Word192 > instance AESKey Word256 unexported which stops you using invalid keys. Someone has asked me to export AESKey as they want to write an explicit type signature for a function they are creating e.g. foo :: AESKey a => a -> Word128 -> Word128 foo x y = encrypt x y but this generates an error. Is there a way of allowing someone to use AESKey in a type signature but not allow them to declare new instances? Thanks, Dominic.

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download haskell?
by Johannes Waldmann 11 Nov '08

11 Nov '08

This is nit-picking, but ... when I go to haskell.org, there is a link (top in the left menu) "Download Haskell". Is this for readers who don't know the meaning of the word "implementation" (a few lines below)? Ah, it must be modelled after the perl.org start page... - J.W.

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Histogram creation
by Alexey Khudyakov 11 Nov '08

11 Nov '08

Hello! I'm tryig to write efficient code for creating histograms. I have following requirements for it: 1. O(1) element insertion 2. No reallocations. Thus in place updates are needed. accumArray won't go because I need to fill a lot of histograms (hundrends) from vely long list of data (possibly millions of elements) and it will traverse input data for each histogram. It seems that I need to use mutable array and/or ST monad or something else. Sadly both of them are tricky and difficult to understand. So good examples or any other ideas greatly appreciated. -- Alexey Khudyakov

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Closed type classes [was: Exporting a Type Class for Type Signatures]
by oleg＠okmij.org 11 Nov '08

11 Nov '08

Dominic Steinitz wrote: > In the crypto package, I have two functions > > encrypt :: AESKey a => a -> Word128 -> Word128 > > decrypt :: AESKey a => a -> Word128 -> Word128 but the class AESKey is not exported, to prevent the user from adding more instances to it. Since AESKey is not exported, the users cannot write signatures that mention that class constraint. The question is, how to export a _closed_ class -- a class the user cannot extend. Chung-chieh Shan and I had a similar problem in our TFP2007 paper: the classes that implement type-level arithmetic must be closed, to prevent the user from declaring that 1+1=1. It seems the best method is to use class aliases: In the implementation of AES, introduce class AESKey a => AESKeyExport a instance AESKey a => AESKeyExport a -- the only instance and now export AESKeyExport (but leave AESKey hidden). If the user needs to write the signature for their function: foo :: AESKeyExport a => a -> Word128 -> Word128 foo x y = encrypt x y they should use the constraint AESKeyExport a. That constraint entails AESKey a, which they cannot mention. The users can try to extend the class ESKeyExport a, but that would do them no good: the library uses the instances of AESKey rather than AESKeyExport. The TFP2007 paper explains that in a bit more detail: http://okmij.org/ftp/Computation/resource-aware-prog/tfp.pdf (Section 2.1). It also mentions a different method, relying on partial type signatures.

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A video of Frag
by Korcan Hussein 11 Nov '08

11 Nov '08

I don't understand why there is no video of Frag online so I made one here: http://uk.youtube.com/watch?v=0jYdu2u8gAU _________________________________________________________________ BigSnapSearch.com - 24 prizes a day, every day - Search Now! http://clk.atdmt.com/UKM/go/117442309/direct/01/

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Haskell Weekly News: Issue 92 - November 8, 2008
by Brent Yorgey 10 Nov '08

10 Nov '08

--------------------------------------------------------------------------- Haskell Weekly News http://sequence.complete.org/hwn/20081108 Issue 92 - November 08, 2008 --------------------------------------------------------------------------- Welcome to issue 92 of HWN, a newsletter covering developments in the [1]Haskell community. GHC 6.10 is released!! Go forth and drool over its new features. Be sure to have the editline libraries (libedit-dev on Debian/Ubuntu, for example) installed before you try building it. Announcements GHC version 6.10.1. Ian Lynagh [2]announced the release of [3]GHC version 6.10.1! This new major release features a number of significant changes, including wild-card patterns, punning, and field disambiguation in record syntax; generalised quasi-quotes; generalised SQL-like list comprehensions; view patterns; a complete reimplementation of type families; parallel garbage collection; a new extensible exception framework; a more user-friendly API; included Data Parallel Haskell (DPH); and more! See [4]the full release notes for more information. new community.haskell.org features: webspace, mailing lists. Ian Lynagh [5]announced that the community server, http://community.haskell.org/, has two new features for hosted projects: project webspace, and project mailing lists. GHC blog. Simon Marlow [6]has set up a [7]GHC blog. This is for all things related to GHC, particularly people working on GHC to blog about what they're up to. If you want a write-bit, sign up for a [8]wordpress account, let Simon know your account name, and blog away! The GHC blog should be syndicated on [9]Planet Haskell soon. Haddock 2.4.0. David Waern [10]announced a [11]new release of [12]Haddock, the Haskell documentation tool. This is a later version than the one shipped with GHC 6.10.1, which is version 2.3.0. That version will not be released on Hackage since it only builds with GHC 6.10.1 (by accident, actually). Besides adding back support for earlier GHC versions, this release contains some more fixes and support for HTML frames. htags-1.0. David Sankel [13]announced the [14]htags package, a tag file generator to enable extra functionality in editors like vim. It expands upon hasktags by using a full Haskell 98 parser and options for recursion. Haskell Quick Reference (1-page PDF). Malcolm Wallace [15]sent a 1-page Haskell quick reference prepared for a recent Haskell tutorial. Permission is granted for anyone to distribute it more widely as they wish, in the hope that it might be useful. Editable sources can be passed along if anyone would like to extend it. Proposal for associated type synonyms in Template Haskell. Thomas van Noort [16]submitted a proposal for adding associated type synonyms to Template Haskell. Comments are welcomed. announce [("InfixApplicative", 1.0), ("OpenGLCheck", 1.0), ("obj", 0.1)]. Thomas Davie [17]announced the upload of a few packages to Hackage which he has produced while working at Anygma. [18]obj-0.1 is a library for loading and writing obj 3D models; [19]OpenGLCheck-1.0 is a micro-package containing instances of Arbitrary for the data structures provided in Graphics.Rendering.OpenGL; and [20]InfixApplicative-1.0 is a second micro-package containing a pair of functions (<^) and (^>) which can be used to provide an infix version of liftA2 applied to an operator. Graphalyze-0.5 and SourceGraph-0.3. Ivan Lazar Miljenovic [21]announced the latest versions of [22]Graphalyze and [23]SourceGraph, which fix a couple of bugs in the previous versions. zlib and bzlib 0.5 releases. Duncan Coutts [24]announced updates to the [25]zlib and [26]bzlib packages, featuring a slightly nicer extended API. The simple API that most packages use is unchanged. There is also a new parameter to control the size of the first output buffer; this lets applications save memory when they happen to have a good estimate of the output size. Discussion Efficient parallel regular expressions. Martijn van Steenbergen [27]asked about efficiently running multiple regular expressions in parallel, leading to an interesting discussion of regular expressions and various parsing methods and libraries. Problems with strictness analysis?. Patai Gergely started an informative [28]discussion about strictness, laziness, strictness analysis, and compiler optimization. If you don't know a lot about these topics but would like to learn, this thread is a good starting point! Jobs 1-year postdoc position in Chalmers Functional Programming group. John Hughes [29]announced a position for a post-doctoral researcher with the Chalmers Functional Programming Group, with a one-year tax-free stipend funded by Intel. The funded project will develop a Domain Specific Language (DSL) for high level modelling, design and analysis of hardware and microarchitectures. Blog noise [30]Haskell news from the [31]blogosphere. * Edward Kmett: [32]Still Alive. Edward is still alive but sadly lost a few recursion scheme posts. =( * >>> Max Rabkin: [33]Beautiful folding. A very cool post about composable folds! * Eric Kow (kowey): [34]timesheet helper. * Philip Wadler: [35]A bizarre function over streams. * David Sankel: [36]Introducing Reactive: Events. A very readable introduction to the Reactive library. I look forward to reading more! * "FP Lunch": [37]Numbers vs Sets. * Mark Jason Dominus: [38]Addenda to recent articles 200810. * Darcs: [39]darcs weekly news #11. * >>> Ken G.: [40]Haskell?. Ken shares some thoughts on Real World Haskell. * Real-World Haskell: [41]Some early reviews. * David Sankel: [42]freeglut + Windows + HOpenGL + HGLUT. * GHC mutterings: [43]GHC 6.10.1 is out!. * Chung-chieh Shan: [44]Cognitive jobs. * London Haskell Users Group: [45]Duncan Coutts: The Haskell Platform. The abstract for Duncan's talk at the London HUG. * Well-Typed.Com: [46]GHC 6.10.1 released!. * Well-Typed.Com: [47]Haskell Platform talk at the London Haskell Users Group. * Mark Wassell: [48]GIS with Haskell 1. * >>> phoenix: [49]Haskell Tricks: Indexing a List. Getting the index of an element satisfying a predicate by zipping. * JP Moresmau: [50]Haskell for counting votes!. JP illustrates five different voting methods with some Haskell implementations. * Ivan Lazar Miljenovic: [51]Graph Theoretic Analysis of Relationships within Discrete Data. * Braden Shepherdson: [52]Pimp Your XMonad #1: Status bars. The first in a planned series of articles on not-so-well-known ways to extend your xmonad configuration. * >>> Cory: [53]Euler and Haskell. Cory just started learning Haskell (a "fun, slightly ridiculous language") via Project Euler. * >>> Sadek Drobi: [54]Code Safety and Correctness is a matter of Mindset Cultured by the Language. * Well-Typed.Com: [55]zlib and bzlib package updates. * >>> Bryan St. Amour: [56]Haskell Solution To The Farmer Problem. * >>> Nathan Hartman: [57]Haskell, Lambert, and the Clarke Ellipsoid. Nathan has started porting a map projection library to Haskell. * David Sankel: [58]Analysis of lazy-stream programs.. Quotes of the Week * Cory: Any language which makes frequent use of monads, functors and has a wikibook describing its relation to category theory is the result of an evil genius (or several, to be precise). * mmorrow: in langs with dependent types, you can just map numbers directly to types instead of having to ride a unicycle along a tightrope while battling an unruly gang of monkeys with knives. * conal: -fsemantics-shemantics * roconnor: all sorts of wonderful things could be done if we are less anal about bottoms. No pun intended. About the Haskell Weekly News New editions are posted to [59]the Haskell mailing list as well as to [60]the Haskell Sequence and [61]Planet Haskell. [62]RSS is also available, and headlines appear on [63]haskell.org. To help create new editions of this newsletter, please see the information on [64]how to contribute. Send stories to byorgey at cis dot upenn dot edu. The darcs repository is available at darcs get [65]http://code.haskell.org/~byorgey/code/hwn/ . References 1. http://haskell.org/ 2. http://article.gmane.org/gmane.comp.lang.haskell.glasgow.user/15591 3. http://www.haskell.org/ghc/ 4. http://haskell.org/ghc/docs/6.10.1/html/users_guide/release-6-10-1.html 5. http://article.gmane.org/gmane.comp.lang.haskell.general/16600 6. http://article.gmane.org/gmane.comp.lang.haskell.glasgow.user/15603 7. http://ghcmutterings.wordpress.com/ 8. http://wordpress.com/ 9. http://planet.haskell.org/ 10. http://www.haskell.org//pipermail/haskell-cafe/2008-November/050271.html 11. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/haddock-2.4.0 12. http://www.haskell.org/haddock 13. http://article.gmane.org/gmane.comp.lang.haskell.general/16582 14. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/htags 15. http://article.gmane.org/gmane.comp.lang.haskell.cafe/47344 16. http://article.gmane.org/gmane.comp.lang.haskell.cafe/47301 17. http://article.gmane.org/gmane.comp.lang.haskell.cafe/47241 18. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/obj 19. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/OpenGLCheck 20. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/InfixApplicative 21. http://article.gmane.org/gmane.comp.lang.haskell.cafe/47171 22. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/Graphalyze 23. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/SourceGraph 24. http://article.gmane.org/gmane.comp.lang.haskell.cafe/47144 25. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/zlib 26. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/bzlib 27. http://thread.gmane.org/gmane.comp.lang.haskell.cafe/47242 28. http://thread.gmane.org/gmane.comp.lang.haskell.cafe/47183 29. http://article.gmane.org/gmane.comp.lang.haskell.general/16596 30. http://planet.haskell.org/ 31. http://haskell.org/haskellwiki/Blog_articles 32. http://comonad.com/reader/2008/still-alive/ 33. http://squing.blogspot.com/2008/11/beautiful-folding.html 34. http://koweycode.blogspot.com/2008/11/timesheet-wishlist.html 35. http://wadler.blogspot.com/2008/11/bizarre-function-over-streams.html 36. http://netsuperbrain.com/blog/posts/introducing-reactive-events/ 37. http://sneezy.cs.nott.ac.uk/fplunch/weblog/?p=114 38. http://blog.plover.com/addenda/200810.html 39. http://blog.darcs.net/2008/11/darcs-weekly-news-11.html 40. http://monolith149daily.blogspot.com/2008/11/haskell.html 41. http://www.realworldhaskell.org/blog/2008/11/06/some-early-reviews/ 42. http://netsuperbrain.com/blog/posts/freeglut-windows-hopengl-hglut/ 43. http://ghcmutterings.wordpress.com/2008/11/05/ghc-6101-is-out/ 44. http://conway.rutgers.edu/~ccshan/wiki/blog/posts/Cognitive_jobs/ 45. http://www.londonhug.net/2008/11/04/duncan-coutts-the-haskell-platform/ 46. http://blog.well-typed.com/2008/11/ghc-6101-released/ 47. http://blog.well-typed.com/2008/11/haskell-platform-talk-at-the-london-hask… 48. http://pound-stone.blogspot.com/2008/11/gis-with-haskell-1.html 49. http://phoenixblitz.blogspot.com/2008/11/haskell-tricks-indexing-list.html 50. http://jpmoresmau.blogspot.com/2008/11/haskell-for-counting-votes.html 51. http://ivanmiljenovic.wordpress.com/2008/11/03/graph-theoretic-analysis-of-… 52. http://braincrater.wordpress.com/2008/11/02/pimp-your-xmonad-1-status-bars/ 53. http://onag.blogspot.com/2008/11/euler-and-haskell.html 54. http://sadekdrobi.com/2008/11/02/code-safety-and-correctness-is-a-matter-of… 55. http://blog.well-typed.com/2008/11/zlib-and-bzlib-package-updates/ 56. http://bryanstamour.com/?p=49 57. http://parsemymonad.blogspot.com/2008/10/haskell-lambert-and-clarke-ellipso… 58. http://netsuperbrain.com/blog/posts/analysis-of-lazy-stream-programs/ 59. http://www.haskell.org/mailman/listinfo/haskell 60. http://sequence.complete.org/ 61. http://planet.haskell.org/ 62. http://sequence.complete.org/node/feed 63. http://haskell.org/ 64. http://haskell.org/haskellwiki/HWN 65. http://code.haskell.org/~byorgey/code/hwn/

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Haskell source packages in Hackage
by Hugo Pacheco 10 Nov '08

10 Nov '08

Hi guys, I am having an hard time installing the haskell-src and haskell-src-exts packages, since both seem to have problems with happy. I have installed happy 1.18.2 successfully, but it does not seem to be visible (although the happy executable is in my path). I get the errors: $ cabal install haskell-src Resolving dependencies... 'haskell-src-1.0.1.3' is cached. Configuring haskell-src-1.0.1.3... Preprocessing library haskell-src-1.0.1.3... cabal: The program happy is required but it could not be found cabal: Error: some packages failed to install: haskell-src-1.0.1.3 failed during the building phase. The exception was: exit: ExitFailure 1 $ cabal install haskell-src-exts Resolving dependencies... 'haskell-src-exts-0.3.9' is cached. Configuring haskell-src-exts-0.3.9... cabal: happy version >=1.17 is required but it could not be found. cabal: Error: some packages failed to install: haskell-src-exts-0.3.9 failed during the configure step. The exception was: exit: ExitFailure 1 Is this some kind of bug in cabal, or in the packages themselves? Thanks, hugo -- www.di.uminho.pt/~hpacheco

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