November 2010 - web-devel

MochaHost for yesod applications?
by Nubis 26 Dec '10

26 Dec '10

I've decided to look for a cheap VPS where I can compile and run yesod applications using the latest and greatest haskell platform. I couldn't find any sane CGI/FastCGI shared host options. I'm even inclined towards developing some sort of heroku.com clone for apps running on WAI so we can solve the deployment issue for most people once and for all. I don't want to go with some obscure hosting I've never heard about and it has to be cheap (Argentinian budget). I've found mochahost has a pretty cheap VPS service with some cool OS choices. http://mochahost.com/vps.php Just thought the information may be useful for someone in the same situation as me, but I would like to hear if anyone has tried mochahost or even found an even more convenient choice for VPS. cheers! ----nubis :)

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Interpolation character in Julius
by Michael Snoyman 20 Dec '10

20 Dec '10

Hamlet, Cassius and (currently) Julius all use a consistent set of characters for interpolation. The dollar sign ($) is for plain scalars, the at sign (@) is for URLs and the caret (^) is for embedding other templates (mixins in the case of Cassius). I like this consistency. Unfortunately, in the case of Julius, the dollar sign is a suboptimal character to use since jQuery uses is so extensively. Currently, to write some simple jQuery Javascript such as: $("h1").hide() you have to use a double dollar sign to achieve escaping, namely: $$("h1").hide() So the questions to the list are: * Is it worth trading consistency for a better choice of interpolation character? * If so, what would be a more optimal interpolation character? I think percent sign (%) might be acceptable. Interpolation is not as important in Julius as it is in Hamlet, so I'm beginning to lean towards replacing the character. Michael

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[Yesod] When POST and create new resource
by いとうかつとし 29 Nov '10

29 Nov '10

Hi I have a question. I think that, when a server receive POST request and create new resource(and URI), the server response is status 201, isn't it? (I'm not really sure about this idea.) On Yesod, How we write to make status201 response?

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ANNOUNCE: yesod-continuations
by Matt Brown 27 Nov '10

27 Nov '10

Hello all, I pushed a new package yesod-continuations to hackage. It allows you to register a handler for one time use (by the session that generated it) at a unique URL. I wrote it as an alternative to subsites for writing yesod widgets with "internal urls" (ajax widgets, for example). A demo (testcont.hs) is included in the source, and the master and continuation branches of my yesod-tailwidget repo compare the two approaches. Feedback is welcome. regards, -matt Hackage: http://hackage.haskell.org/package/yesod-continuations-0.1 GitHub: https://github.com/softmechanics/yesod-continuations yesod-tailwidget GitHub: https://github.com/softmechanics/yesod-tailwidget

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Yesod Form
by Dmitry Olshansky 25 Nov '10

25 Nov '10

Hello all, can I handle a form with more than one button in Yesod? In this case pair (button_name, button_value) is sent to the server on submit. Can I get it in some way? Best regards, Dmitry

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[Yesod?][Chromium?] file-echo.lhs on chromium
by いとうかつとし 24 Nov '10

24 Nov '10

Hi now, I runhaskell file-echo.lhs sample which in yesoddocs/yesod/tutorials, and check it on firefox and chromium browsers. On firefox, I confirm the program works good for varias type files. But, on chromium, i get error for same uploaded files which has no extensions like as README, TODO, LICENSE, ... when, I modify file-echo.lhs as below in order to get a log. --- postHomepage = do rr <- getRequest liftIO $ putStrLn "OK" -- Logging (_, files) <- liftIO $ requestBody rr fi <- maybe notFound return $ lookup "file" files liftIO $ do -- Logging putStrLn $ fileName fi putStrLn $ fileContentType fi return [(fileContentType fi, toContent $ fileContent fi)] --- On chromium, this handler function success to putStrLn "OK", but fail to putStrLn the others. I'd like to check HTTP headers, But i couldn't find my POST request in "Resources". The developer tool on chromium, my POST request is replaced by a request for 'chrome://chromewebdata/' Anyone knows this problem?

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Re: State in Yesod
by Michael Snoyman 24 Nov '10

24 Nov '10

On Wed, Nov 24, 2010 at 6:04 PM, Dmitry Olshansky <olshanskydr(a)gmail.com> wrote: > Hello all, > > can I save in Yesod on server-side some information between different > requests (State)? > I haven't found how to do this. Yes you can, but not by using a State monad. You basically have two choices: * Store inside the Yesod process, using something like an MVar or TVar. This will work fine, unless you are using multiple Yesod processes to serve requests (odds are, you aren't). * Store state in the database. But if you just want to store a small amount of data about the user, you can use the session, which stores the data encrypted in a cookie. I can give you better advice if I know what the purpose of this is. Michael

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IDEA: wai-vhost
by Michael Snoyman 23 Nov '10

23 Nov '10

Just thought I'd throw out an idea I've been bouncing around and see if anyone would be interested in either using or implementing it. Basically, it allows multiple WAI applications to be run as a single app and switch which app responds to a request based upon the Host, the same way virtual hosting works in web servers like nginx, Apache or lighttpd. I would imagine the type signature would look something like: vhost :: [(String, Application)] -> Application -> Application The first argument would be a list of applications and their respective virtual hosts (this would probably be better as a Map for performance, kind of irrelevant at this point). The second argument would be the default application to run when none of the vhosts match. This could even just be an app that always returns a 404. It returns a new application handles all of this transparently. I can see two immediate uses: * Instead of running a whole bunch of WAI fastcgi processes on a server, you could run just a single process that automatically deals out requests to the right app. This would save on memory usage, especially when your apps are all sharing the same Haskell libraries. * Instead of needing a dedicated web server like nginx to handle vhosting, you could use the Snap handler with this and be running a pure Haskell stack. Advantage would be easier maintenance, plus better performance from cutting out the middleman. At this point, it's just an idea. I don't think it's hard to implement, but I wouldn't mind some feedback first. And if someone else wants to take a crack at it, please speak up! I wouldn't mind having one less package to maintain. Michael

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[Yesod] failed : cabal install yesod-examples
by いとうかつとし 21 Nov '10

21 Nov '10

I'll install yesod-examples. But cabal install yesod-examples failed. Error Messages are here. ---- Linking dist/build/form/form ... yesod/tutorial/mkToForm.hs:11:7: Could not find module `MkToForm': Use -v to see a list of the files searched for. cabal: Error: some packages failed to install: yesod-examples-0.6.0 failed during the building phase. The exception was: ExitFailure 1 --- The mkToForm.hs's line 11 is 'import MkToForm'. You success to compile this?

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GHandler in forms
by Max Cantor 17 Nov '10

17 Nov '10

i didn't event realize that GHandler was in the GForm monad stack. knowing that, I would definitely like to use it. max

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