January 2006 - Libraries

RE: Idea to allow people to comment on Haskell docs
by Simon Peyton-Jones 09 Jan '07

09 Jan '07

| I've had a go at patching Haddock to put a link on the page for each | module. It's controlled by an optional --wiki=URL flag. | | As an example, I used this with the (devel version of the) Gtk2Hs docs: | | http://haskell.org/gtk2hs/docs/devel/ | | For example this page: | | http://haskell.org/gtk2hs/docs/devel/Graphics-Rendering-Cairo-SVG.html It looks great! But I'd never have found the link if you hadn't pointed me at it. Rather than "Wiki" say "User comments". And I think the per-entry [User comment] link is essential. Typically people are going to be looking at a particular thing. For example, here http://haskell.org/gtk2hs/docs/devel/Graphics-Rendering-Cairo-SVG.html#v %3AsvgRenderFromString is where I'd look for the link for svgRenderFromString. Does MediaWiki support anchors in the middle of a page? That's essential here -- we want one Wiki page for one Haddock page. On a closely related matter, Benjamin Pierce told me how often he wished that there was a link from the Haddock documentation to the source code for a function. Especially for Prelude functions, he's dead right. So another really useful Haddock enhancement would be the ability to add links to the source code from the Haddock docs --- again on a per-function basis. Do you feel like adding that too? Where should the code live? I'd suggest snap-shoting it at the moment that the Haddock docs are generated, and putting the files with the Haddock docs. Simon

12 15

external core
by John Meacham 22 Mar '06

22 Mar '06

Now, the external core feature of ghc is great, but it is not utilized very much. The main reason I think is that there is a large barrier to entry in writing something that uses it since you need to parse/generate it. It would be nice if there were a standard library that came with ghc (or cabalized and portable even better) that could parse and pretty print external core. ideally, one could write a simple pass-through core processor that interacts with ghc in a single line and someone working on a new optimization need only worry about that. Also, it would make it very easy for jhc to generate and parse ghc core files (always an ulterior motive). I wanted to use jhcs front end to generate ghc core so I could get a true measure of the difference in just their back-end performance without taking into account ghc's superior high-level optimizations. In any case. I think all the code is out there in ghc and it just needs to be separated and cabalized. I know there was talk of creating a ghc internals library, but it would be nice if this code were portable and independent. John -- John Meacham - ⑆repetae.net⑆john⑈

3 4

Trie implementation
by Keith Wansbrough 11 Mar '06

11 Mar '06

Hi... I was writing some code yesterday to walk over a directory tree, and needed a Trie. Not seeing one around, I wrote a basic implementation of the functions I needed (attached below). Has anyone else done this? Should I polish it up and offer it for inclusion in Data? --KW 8-)

7 8

brainstorming ways to stabalize Cabal interface?
by Isaac Jones 02 Feb '06

02 Feb '06

Greetings. I'm keen to try to stabalize more of the Cabal interface, but I'm not sure the best way to go about that. I started a wiki page to start to document what is stable and what is not. Eventually this should move into the end-user documentation: http://hackage.haskell.org/trac/hackage/wiki/StableInterfaces Does anyone have clever ideas for how to go about pushing these interfaces toward stability? Do we just need to declare that certain things are unstable for the near-term (and possibly implement the eternal compatibility in theory idea[1]) and continue to experiment with them until they seem done enough? Do we stare at them very hard? Below[2] are my thoughts about what we _know_ to be stable, and the types for the new hooks interface. peace, isaac [1] http://www.haskell.org/tmrwiki/EternalCompatibilityInTheory [2] Here's a summary of the bits of interface that need to be stabalized, or are already stabalized. Stable Commands * ./setup configure o --prefix o --user o --ghc, --hugs o --verbose * ./setup build * ./setup install Unstable Commands * everything else. well, they're really _pretty_ stable. Stable functions * defaultMain * defaultMainWithHooks defaultUserHooks o but regular defaultMainWithHooks isn't stable since userHooks changes. Unstable functions * Various utility functions * UserHooks runTests :: Args -> Bool -> PackageDescription -> LocalBuildInfo -> IO ExitCode, -- ^Used for @.\/setup test@ readDesc :: IO (Maybe PackageDescription), -- ^Read the description file hookedPreProcessors :: [ PPSuffixHandler ], -- ^Custom preprocessors in addition to and overriding 'knownSuffixHandlers'. hookedPrograms :: [Program], -- ^These programs are detected at configure time. Arguments for them are added to the configure command. -- |Hook to run before configure command preConf :: Args -> ConfigFlags -> IO HookedBuildInfo, -- |Over-ride this hook to get different behavior during configure. confHook :: PackageDescription -> ConfigFlags -> IO LocalBuildInfo, -- |Hook to run after configure command postConf :: Args -> ConfigFlags -> PackageDescription -> LocalBuildInfo -> IO ExitCode, ... * Everything else peace, isaac

5 8

building haddock?
by Malcolm Wallace 01 Feb '06

01 Feb '06

Quick question: how do I build Haddock from the darcs repo? Long version: Using Cabal as provided with ghc-6.4.1 gave me this error: $ ghc-6.4.1 --make Setup $ ./a.out configure --help a.out: Line 12: Unknown field 'data-files' So I tried to upgrade Cabal to a newer version. Following the instructions to the letter, there was some weirdness with compiler versions, but I did end up with a newer Cabal: $ cd cabal-1.1.3 $ ghc-pkg-6.4.1 unregister Cabal Saving old package config file... done. Writing new package config file... done. $ vi GNUMakefile # edit HC=ghc-6.4.1, HC_PKG=ghc-pkg-6.4.1 $ make install mkdir -p dist/tmp ghc-6.4.1 --make -Wall -fno-warn-unused-matches -cpp -i. -odir dist/tmp -hidir dist/tmp Setup.lhs -o setup ... ./setup configure --ghc --prefix=/usr/malcolm/local Configuring Cabal-1.1.3... configure: Using install prefix: /usr/malcolm/local configure: Using compiler: /grp/haskell/bin/ghc # this is wrong configure: Compiler flavor: GHC configure: Compiler version: 6.2.2 # eek! this is wrong configure: Using package tool: /grp/haskell/bin/ghc-pkg # this is wrong too ... ./setup install Installing: /usr/malcolm/local/lib/Cabal-1.1.3/ghc-6.2.2 & /usr/malcolm/local/bin Cabal-1.1.3... # installed for wrong compiler Registering Cabal-1.1.3... Reading package info from ".installed-pkg-config"done. Expanding embedded variables... done. Saving old package config file... done. Writing new package config file... done. # Cabal is missing from ghc-6.4.1 $ ghc-pkg-6.4.1 -l /usr/malcolm/local/lib/ghc-6.4.1/package.conf: rts-1.0, base-1.0, haskell98-1.0, template-haskell-1.0, unix-1.0, parsec-1.0, haskell-src-1.0, network-1.0, QuickCheck-1.0, HUnit-1.1, mtl-1.0, fgl-5.2, X11-1.1, HGL-3.1, OpenGL-2.0, GLUT-2.0, stm-1.0, readline-1.0, (lang-1.0), (concurrent-1.0), (posix-1.0), (util-1.0), (data-1.0), (text-1.0), (net-1.0), (hssource-1.0) # ...but is installed for ghc-6.2.2 $ ghc-pkg-6.2.2 -l /grp/haskell/lib/ghc-6.2.2/package.conf: rts, base, haskell98, haskell-src, network, parsec, QuickCheck, readline, unix, lang, concurrent, posix, util, data, text, net, hssource, hat, HaXml, wxcore, wx, Cabal But the killer is, it still doesn't work: $ cd haddock $ ghc-6.2.2 --make Setup -package Cabal Chasing modules from: Setup Compiling Main ( Setup.lhs, Setup.o ) Linking ... $ ./a.out t configure --help a.out: haddock.cabal:12: Unknown field 'data-files' So then I tried just building haddock directly with ghc: $ ghc-6.4 --make Main.hs Chasing modules from: Main.hs Main.hs:39:1: lexical error $ ghc-6.4 --make -cpp Main.hs Chasing modules from: Main.hs Could not find module `Paths_Haddock': use -v to see a list of the files searched for (imported from Main.hs) And now I'm stuck. There genuinely is no module called Paths_Haddock. Regards, Malcolm

4 5

RE: Idea to allow people to comment on Haskell docs
by Simon Peyton-Jones 29 Jan '06

29 Jan '06

| > Adding source code links would complete the picture. | | Done! | | Take a look at my example pages again: | http://haskell.org/gtk2hs/docs/devel/ | http://haskell.org/gtk2hs/docs/devel/Graphics-Rendering-Cairo-SVG.html | http://haskell.org/gtk2hs/docs/devel/Graphics-Rendering-Cairo-SVG.html#v :svgRender Excellent stuff! I didn't follow all the details of your message, but I notice that the source code link doesn't move to the defn, presumably because there's no anchor in the source file. I guess that would require munging the source files to add the anchors? Unless one can link to "Foo.hs line 424", somehow. Suppose I follow the Comments link from (say) withSvgFromFile, and add some comments. Will they automatically get the right anchor? Because all the comments for SVG (rightly) end up in a single file, don't they? This looks great. (Don't forget the documentation for Haddock itself. Documenting the feature makes it much more likely that people will use it.) Simon

3 2

list sorting
by John Meacham 25 Jan '06

25 Jan '06

is there a function floating around for _efficiently_ sorting a list of lists that will not evaluate any more of the lists than is needed to sort them properly and does not re-compare the common prefix of said lists? as in, sortLists :: Ord a => [[a]] -> [[a]] sortLists = ... if it proves faster in the general case than 'sort', then a RULES pragma might be in order to use it instead when sorting lists. a very common case being sorting strings. John -- John Meacham - ⑆repetae.net⑆john⑈

4 4

RE: Idea to allow people to comment on Haskell docs
by Simon Peyton-Jones 23 Jan '06

23 Jan '06

| They will get the right anchor if people follow the convention of using | headings for each function they want to add notes about. In the wiki | markup that means writing: | | = withSvgFromFile = Aha. It'd be good if the text they see when they are about to start editing a blank comment file gave them exactly this advice. Don't know if that is possible, but that's the moment they'll need it! Simon

2 1

Re: [Haskell] duplicate elements in Data.Set
by Jean-Philippe Bernardy 22 Jan '06

22 Jan '06

I'd say your compare function isn't transitive. If you can tell it's well behaved, and if you can send me even your complicated example, I'll look into it. Cheers, JP. On 1/21/06, Walter Moreira <gwallter(a)gmail.com> wrote: > Hello list. Are there situations where a set can contain duplicate > elements? > > I have a newtype and it is an instance of 'Eq' via the 'compare' method, > and it is also an instance of 'Ord'. After some Data.Set operations > with sets of that type I get a set which contains two elements which > compare equal. What am I doing wrong? > > The function 'Set.valid' returns 'False' when applied to the set. I > use the function 'Set.fromList' sometimes. Is it supposed to always > yield a valid set? or it may depend on the order or equality? > > Sorry the question is a little vague. When I try to construct small > examples the problem disappear. > > Thanks, > Walter > _______________________________________________ > Haskell mailing list > Haskell(a)haskell.org > http://www.haskell.org/mailman/listinfo/haskell >

2 1

RE: Idea to allow people to comment on Haskell docs
by Simon Peyton-Jones 22 Jan '06

22 Jan '06

I think it looks great! Just the job, thank you. Did you modify the Haddock documentation too? One thing to think about is what happens as the code evolves. When you re-generate the Haddock docs, what happens? Since the links are done by name (I think) it's probably not bad: you get links to the existing wiki entries so long as the name of the function doesn't change. If a function is deleted, I guess there'll be an orphan wiki entry, but that's probably ok. Worth documenting this in the Haddock docs. Adding source code links would complete the picture. Simon | -----Original Message----- | From: Duncan Coutts [mailto:duncan.coutts@worc.ox.ac.uk] | Sent: 19 January 2006 21:55 | To: Simon Peyton-Jones | Cc: Haskell Libraries | Subject: RE: Idea to allow people to comment on Haskell docs | | On Wed, 2006-01-18 at 09:01 +0000, Simon Peyton-Jones wrote: | > It looks great! But I'd never have found the link if you hadn't pointed | > me at it. | > | > Rather than "Wiki" say "User comments". | | Done. | | > And I think the per-entry [User comment] link is essential. Typically | > people are going to be looking at a particular thing. For example, here | > | > http://haskell.org/gtk2hs/docs/devel/Graphics-Rendering-Cairo-SVG.html#v :svgRenderFromString | > is where I'd look for the link for svgRenderFromString. | | Done! | | So take another look at these example pages: | http://haskell.org/gtk2hs/docs/devel/ | http://haskell.org/gtk2hs/docs/devel/Graphics-Rendering-Cairo-SVG.html | | For the per-entry links, to conserve space I've just said [Comments] | rather than [User Comments] and used a smaller font. These cosmetic | things are easy to change if anyone complains. | | I've sent the haddock patches that implement this stuff to Simon Marlow, | so if people are generally favourable of this iteration of the patch | perhaps he'd like to apply it. :-) I hope I've done the changes in such | a way that it should be straightforward to add source code links too | if/when haddock is taught how to find the original source file for each | module. | | So, opinions? | | Duncan

2 2