- Haskell-Cafe - Haskell.org

Emacs mode for Happy?
by Edward Amsden 03 Dec '10

03 Dec '10

I'm planning on using Happy for my compiler construction class this quarter. The only problem so far is that emacs keeps trying to mangle my .y files because it assumes I mean them for yacc. Is there an emacs mode for Happy or is it maybe time to also buckle down to learning elisp and write one myself? ------ Edward Amsden Undergraduate Computer Science Rochester Institute of Technology

1 0

Most images broken on haskellwiki pages
by Eugene Kirpichov 03 Dec '10

03 Dec '10

Hello. I looked at a couple pages of mine http://www.haskell.org/haskellwiki/Splot , http://www.haskell.org/haskellwiki/Timeplot , and at a couple of random pages http://haskell.org/haskellwiki/Special:Random - and looks like the vast majority of images are not displaying. What's wrong? Does it have to do with the wiki redesign? What should, say, I personally do about my images regarding this? -- Eugene Kirpichov Senior Software Engineer, Grid Dynamics http://www.griddynamics.com/

4 6

Re: [Haskell-cafe] [Haskell] haskell.org migration complete
by Simon Marlow 03 Dec '10

03 Dec '10

On 02/12/2010 23:48, Claus Reinke wrote: >> The haskell.org server migration is now complete. >> Please let us know if you have any problems. > > Beginning this week, the majority of mails from haskell.org > lists seem to end up in my ISP's spam filter. That would be > Yahoo! - I wonder whether others here have seen a similar > effect when checking their spam filters? > > I don't know whether this is caused by the migration, but > it made me wonder about something I recalled reading > about whitelisting mailing list senders with ISPs, and a > little search found the following: > > http://en.wikipedia.org/wiki/Whitelist > http://help.yahoo.com/l/us/yahoo/mail/postmaster/basics/ > http://help.yahoo.com/l/us/yahoo/mail/postmaster/forms_index.html > http://help.yahoo.com/l/us/yahoo/mail/postmaster/bulkv2.html > http://www.novablog.info/2008/10/21/5-simple-steps-to-improving-e-mail-deli… > > > So it might be related to the new server. Is whitelisting > something the mailing list hosting service should deal > with, or is that left to the customer? I'm fairly sure GMail at least whitelists haskell.org, because I get spam sent via the <list>-owner(a)haskell.org aliases that invariably ends up in my inbox, apparently bypassing GMail's usually very good spam filtering. Cheers, Simon

1 0

Manatee Video.
by Andy Stewart 03 Dec '10

03 Dec '10

Hi all, Many people ask "What's Manatee?" A video worth a thousand words : here is video (select 720p HD) http://www.youtube.com/watch?v=weS6zys3U8k And i think the correct answer to "What's Manatee?" should be : Depend on you how to use it. :) Other information look : http://hackage.haskell.org/package/manatee Enjoy! -- Andy

4 8

How to cabal fetch mtl==2.0.0.0?
by Iain Alexander 02 Dec '10

02 Dec '10

<log> F:\Util\Haskell>cabal fetch mtl==2.0.0.0 Resolving dependencies... cabal: internal error: could not construct a valid install plan. The proposed (invalid) plan contained the following problems: The following packages are involved in a dependency cycle transformers-0.2.2.0, special-functors-1.0, mtl-2.0.0.0 F:\Util\Haskell>cabal -V cabal-install version 0.8.2 using version 1.8.0.2 of the Cabal library </log> Could someone please remind me of the correct incantation to make this work. (I observe that transformers-0.1.4.0 optionally (by cabal flag) depends on special-functors, and special-functors-1.0 depends on mtl. So given that mtl-2 no doubt depends on transformers, I can see the potential for confusion, but there presumably must be a way of breaking the (apparent) loop.) TIA, Iain. -- Iain Alexander ia(a)stryx.demon.co.uk

9 15

Monadic design patterns for the web Kickstarter project
by Greg Meredith 02 Dec '10

02 Dec '10

Dear Haskellians, Last week i went in to record the 2nd and 3rd installments of the C9 monadic design patterns for the web videos. Charles Torre, the series producer, told me there were over 40K distinct views of the first video. i know that many of them came from this community. So, i really want to say thanks! i also want to mention that i just initiated a Kickstarter project<http://www.kickstarter.com/projects/1499410734/monadic-design-patterns-for-…>to raise enough money to complete the book. i've been finding that i'm at a point where the book needs a certain level of focus that doesn't mix well with juggling a ton of clients. i'm trying to raise just enough that i can clear off my desk and focus on completing the book and the source code that supports it. So, if it's of interest please let your friends and cronies know and donate yourself, if you can. For your amusement, here's a little video about it <http://www.youtube.com/watch?v=qOj0tgQDSeQ>. Best wishes, --greg -- L.G. Meredith Managing Partner Biosimilarity LLC 7329 39th Ave SW Seattle, WA 98136 +1 206.650.3740 http://biosimilarity.blogspot.com -- L.G. Meredith Managing Partner Biosimilarity LLC 1219 NW 83rd St Seattle, WA 98117 +1 206.650.3740 http://biosimilarity.blogspot.com

1 0

Fwd: typehash patch for base >= 4 && < 4.4
by Andrew Miller 02 Dec '10

02 Dec '10

Hi all, Typehash 1.4.0.0, the latest version of typehash in hackage, has a cabal constraint base < 4, making it difficult to use with packages that only support newer base versions. I sent a patch to fix this to the maintainer for the typehash package (Lennart Augustsson) on the 16th of November, but haven't heard anything back - it is possible that he doesn't read the e-mail address I sent it to, or is no longer interested in maintaining typehash. Does anyone who would be willing to know Lennart in person to confirm this? Failing this, does anyone want to be maintainer for the typehash package? If I don't hear any better ideas, I could simply upload a version 1.4.0.1 with my split base patch applied, and the maintainer changed to "haskell-cafe(a)haskell.org". Best wishes, Andrew -------- Original Message -------- Subject: typehash patch for base >= 4 && < 4.4 Date: Tue, 16 Nov 2010 17:55:13 +1300 From: Andrew Miller <andrew(a)amxl.com> To: lennart(a)augustsson.net diff -rbud typehash-1.4.0.0/src/Data/TypeHash.hs typehash-1.4.0.1/src/Data/TypeHash.hs --- typehash-1.4.0.0/src/Data/TypeHash.hs 2009-10-06 03:43:44.000000000 +1300 +++ typehash-1.4.0.1/src/Data/TypeHash.hs 2010-11-16 17:43:51.917333177 +1300 @@ -44,7 +44,7 @@ data Type = Name { typeName :: String } -- Abstract type, or recursive reference - | Data { typeName :: String, constrs :: [Constructor] } + | Data { typeName :: String, dconstrs :: [Constructor] } deriving (Eq, Ord, Show, Typeable, Data) type Constructor = (String, [Field]) type Field = (String, Type) -- a unique number is used for missing field names @@ -54,7 +54,7 @@ let tn = show $ fullTypeOf x in case dataTypeRep $ dataTypeOf x of AlgRep cs | tn `notElem` tns -> - Data { typeName = tn, constrs = map (gConstr (tn:tns) x) cs } + Data { typeName = tn, dconstrs = map (gConstr (tn:tns) x) cs } _ -> Name { typeName = tn } -- Use type name for truly abstract types and recursive types. gConstr :: (Data a) => [String] -> a -> Constr -> (String, [Field]) Only in typehash-1.4.0.1/src/Data: TypeHash.hs~ diff -rbud typehash-1.4.0.0/typehash.cabal typehash-1.4.0.1/typehash.cabal --- typehash-1.4.0.0/typehash.cabal 2009-10-06 03:43:44.000000000 +1300 +++ typehash-1.4.0.1/typehash.cabal 2010-11-16 17:40:55.496953710 +1300 @@ -1,5 +1,6 @@ Name: typehash -Version: 1.4.0.0 +Cabal-Version: >= 1.2 +Version: 1.4.0.1 License: BSD3 Author: Lennart Augustsson Maintainer: Lennart Augustsson @@ -10,6 +11,18 @@ Description: Produce a hash for a type that is unique for that type. The hash takes both actual type names and type structure into account. This is useful for checking the type of persisted values. -Hs-Source-Dirs: src -Build-Depends: base < 4, mtl, bytestring, pureMD5, binary -Exposed-modules: Data.TypeHash + +Flag base4 + Description: Use base-4.* + Default: True + +Library + Hs-Source-Dirs: src + Build-Depends: mtl, bytestring, pureMD5, binary + If flag(base4) + Build-Depends: + base >= 4 && < 4.4, + syb < 0.3 + else + Build-Depends: base < 4 + Exposed-modules: Data.TypeHash

2 1

Managing multiple installations of GHC
by Robert Clausecker 02 Dec '10

02 Dec '10

Hi folks! I want to test the new version 7 of GHC, but don't want to replace the packaged version 6.12 with it. I'm not very advanced with the internals of GHC and have some problems. So these are my questions: I installed GHC into a subdir of my homedir, let's call it ~/ghc7. How can I install additional libs there? How can I install GHC 7 parallel to GHC 6.12 with the option to choose? My OS is GNU/Linux, my Distro is Ubuntu (Lucid). Thank you very much, yours Robert Clausecker

5 4

doesDirectoryExist is always returning False
by Marcelo Sousa 02 Dec '10

02 Dec '10

Hi, I'm having currently a problem with System.Directory in my mac os. System Version: Mac OS X 10.6.5 Kernel Version: Darwin 10.5.0 Prelude System.Directory> let dirTest = do {dir <- getCurrentDirectory; doesDirectoryExist dir} Prelude System.Directory> dirTest False I noticed also that I can't change the searchable field in the permissions record. Prelude System.Directory> getPermissions "." Permissions {readable = True, writable = True, executable = True, searchable = False} I tried different versions of directory and filepath packages but with no success at the moment. Any suggestions?! Regards, Marcelo Sousa

4 4

Haskell Weekly News: Issue 160 - December 1, 2010
by Daniel Santa Cruz 02 Dec '10

02 Dec '10

Welcome to issue 160 of the HWN, a newsletter covering developments in the [1]Haskell community in the week of November 21 - 27. My apologies for proving a much shorter version of the weekly news this time around. I'm really short on time this week, but decided to send this abbreviated version rather than skipping it. Hope to resume full coverage next week. Cheers! Top Reddit Stories * Lisk - Lisp and Haskell Domain: chrisdone.com Score: 70, Comments: 83 On Reddit: http://www.reddit.com/r/haskell/comments/ec0kp/lisk_lisp_and_haskell/ Original: http://chrisdone.com/posts/2010-11-25-lisk-lisp-haskell.html * lazycatmanatee is building a enormous suite of graphical, desktop apps in Haskell. Here's the screenshot feed Domain: flickr.com Score: 58, Comments: 11 On Reddit: http://www.reddit.com/r/haskell/comments/eb5kd/lazycatmanatee_is_building_a… Original: http://www.flickr.com/photos/48809572@N02/ * Category theory for Haskell programmers Domain: geoffhulette.wordpress.com Score: 49, Comments: 7 On Reddit: http://www.reddit.com/r/haskell/comments/eatd6/category_theory_for_haskell_… Original: http://geoffhulette.wordpress.com/2010/11/22/category-theory-for-haskell-pr… * Duck typing in Haskell Domain: chrisdone.com Score: 45, Comments: 10 On Reddit: http://www.reddit.com/r/haskell/comments/ea99a/duck_typing_in_haskell/ Original: http://chrisdone.com/posts/2010-11-22-duck-typing-in-haskell.html * GHC 7 I/O manager status update: bugs fixed, performance improved, plans afoot! Domain: serpentine.com Score: 41, Comments: 0 On Reddit: http://www.reddit.com/r/haskell/comments/ecls3/ghc_7_io_manager_status_upda… Original: http://www.serpentine.com/blog/2010/11/27/ghc-7-io-manager-status/ * And here I thought they were using Haskell... Domain: i.imgur.com Score: 34, Comments: 11 On Reddit: http://www.reddit.com/r/haskell/comments/ebgnj/and_here_i_thought_they_were… Original: http://i.imgur.com/ApzhX.png * Fun with monad comprehensions Domain: blog.n-sch.de Score: 33, Comments: 9 On Reddit: http://www.reddit.com/r/haskell/comments/ecu0w/fun_with_monad_comprehension… Original: http://blog.n-sch.de/2010/11/27/fun-with-monad-comprehensions/ * The 'text' package has been accepted into the Haskell Platform! Domain: self.haskell Score: 31, Comments: 20 On Reddit: http://www.reddit.com/r/haskell/comments/eb7fd/the_text_package_has_been_ac… Original: /r/haskell/comments/eb7fd/the_text_package_has_been_accepted_into_the/ * Yesod 0.6.3 Released Domain: docs.yesodweb.com Score: 24, Comments: 1 On Reddit: http://www.reddit.com/r/haskell/comments/e9jfd/yesod_063_released/ Original: http://docs.yesodweb.com/blog/yesod-0-6-3/ * how subtraction works for combinatorial species Domain: byorgey.wordpress.com Score: 24, Comments: 2 On Reddit: http://www.reddit.com/r/haskell/comments/ec5mx/how_subtraction_works_for_co… Original: http://byorgey.wordpress.com/2010/11/24/species-subtraction-made-simple/ Top StackOverflow Questions * Avoiding namespace pollution in Haskell votes: 14, answers: 3 http://stackoverflow.com/questions/4260507/avoiding-namespace-pollution-in-… * Keeping State in a Stateless world votes: 7, answers: 2 http://stackoverflow.com/questions/4259800/keeping-state-in-a-stateless-wor… * Updating a Big State Fast in Haskell votes: 7, answers: 2 http://stackoverflow.com/questions/4265660/updating-a-big-state-fast-in-has… * What is the most efficient purely functional algorithm for generating all prefixes of a list? votes: 7, answers: 2 http://stackoverflow.com/questions/4290370/what-is-the-most-efficient-purel… * How can I make a graphical command line in haskell/gtk2hs? votes: 6, answers: 2 http://stackoverflow.com/questions/4281984/how-can-i-make-a-graphical-comma… * Point-free form versus style votes: 5, answers: 3 http://stackoverflow.com/questions/4235741/point-free-form-versus-style * How to catch (and ignore) a call to the error function? votes: 4, answers: 2 http://stackoverflow.com/questions/4243117/how-to-catch-and-ignore-a-call-t… * Persistent console history in ghci votes: 4, answers: 1 http://stackoverflow.com/questions/4249351/persistent-console-history-in-gh… * Common Lisp equivalent to Haskell's main function? votes: 4, answers: 2 http://stackoverflow.com/questions/4285718/common-lisp-equivalent-to-haskel… * How can I write a MST algorithm (Prim or Kruskal) in Haskell? votes: 4, answers: 3 http://stackoverflow.com/questions/4290163/how-can-i-write-a-mst-algorithm-… About the Haskell Weekly News New editions are posted to [2]the Haskell mailing list as well as to [3]the Haskell Sequence and [4]Planet Haskell. [5]RSS is also available, and headlines appear on [6]haskell.org. To help create new editions of this newsletter, please send stories to dstcruz * at * gmail * dot * com. The code used to produce this version of the newsletter is not yet publicly available, as it is a complete hack designed to get things started again. Until next time, Daniel Santa Cruz References 1. http://haskell.org/ 2. http://www.haskell.org/mailman/listinfo/haskell 3. http://sequence.complete.org/ 4. http://planet.haskell.org/ 5. http://sequence.complete.org/node/feed 6. http://haskell.org/

1 0