- web-devel - Haskell.org

[Yesod] Bookmarklet web app development.
by William Pearson 21 Feb '11

21 Feb '11

Hi, I'm trying to figure out the best way to do a webapp based around a bookmarklet. This means I am slightly out on the left field. The bookmarklet requests a javascript file which should be customized on a per user basis (based on session). I've been fiddling about with Yesod and have come across Julius and renderJulius, which I hoped would be able to do what I wanted, but I am coming to the conclusion that it is harder than I thought. My current thinking is that I might be able to do something using getCurrentRoute and judicious monadic magic, but I suspect I am tying myself up in knots. I'd like to keep type safe urls if possible. Thanks for any help, Will

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[Yesod] database tables migration problem.
by Katsutoshi Itoh 20 Feb '11

20 Feb '11

Hi I am developping web service *incrementally* by using devel-server. This is very good feel. but, a bit problem occurred, when the program install and setup new mathine. This service's Model.hs has 2 tables these are cross-reference like as below. User : avatar FileHeaderId Update : FileHeader : creator UserId : i settled like ... 1. migrate tables which has no column without id. 2. alter add columns. i think yesod should separate the migration to 2 steps. 1 is to create tables these has no columns without id. 2 is to add colums and so on. How about this?

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[Yesod] sendFile depends on approot?
by Katsutoshi Itoh 20 Feb '11

20 Feb '11

Hi when i set approot = "http://foo.bar.buz/quz", then favicon.ico could not get at web brawser. is this a bug? i use yesod 0.6.7.

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[Yesod] Where is Yesod.Helpers.Crud on Yesod 0.7.1
by Katsutoshi Itoh 20 Feb '11

20 Feb '11

I'm trying 0.7.1. Which library has Yesod.Helpers.Crud?

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How exactly do you add cassius files to a hamlet template?
by Ian Duncan 17 Feb '11

17 Feb '11

I assumed that I could change: defaultLayout widget = do mmsg <- getMessage pc <- widgetToPageContent $ do widget addCassius $(Settings.cassiusFile "default-layout") hamletToRepHtml $(Settings.hamletFile "default-layout") To: defaultLayout widget = do mmsg <- getMessage pc <- widgetToPageContent $ do widget addCassius $(Settings.cassiusFile "other-stuff") addCassius $(Settings.cassiusFile "default-layout") hamletToRepHtml $(Settings.hamletFile "default-layout") And that it would minify other-stuff.cassius and include it, but this is clearly wrong. I also tried this: defaultLayout widget = do mmsg <- getMessage pc <- widgetToPageContent $ do widget addCassius $(Settings.cassiusFile "other-stuff") hamletToRepHtml $(Settings.hamletFile "default-layout") Replacing default-layout completely, and it didn't work either. What am I doing wrong here?-- Ian Duncan

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Haskell Web Framework Happstack 6 Released
by Jeremy Shaw 17 Feb '11

17 Feb '11

Hello, I am pleased to announce the release of Happstack 6. We fully recommend that all Happstack users migrate to the new release. Happstack is a high-performance Haskell web framework. It has high- level functionality for routing requests, extracting parameters, manipulating responses, serving static file contents, compression responses, and more. It includes an integrated HTTP server and a native RAM-cloud database system known as MACID. This allows you to deploy your web application with out having to configure apache, php, mysql, memcached, etc! Install instructions can be found here: http://happstack.com/download If you are porting existing applications you should check out the Happstack 6 migration guide: http://code.google.com/p/happstack/wiki/Happstack6Migration Porting should be pretty straight-forward. Despite the massive reorganization, the exports from Happstack.Server are largely the same. What's Exciting! ---------------- The focus of this release has been happstack-server. The primary goal was to make happstack-server much easier to learn and to use. This includes: 1. improving the overall organization of the library 2. greatly improving the documentation 3. making it easier to install 4. ensuring that the server provides fast, reliable performance 5. making it easier for new (and old) developers to understand and get started If you have looked at Happstack before and found it too difficult to understand, I highly recommend you take another look. The new organization and documentation make it far easier to understand. More Logical Organiation ------------------------ In prior versions, the Happstack.Server.SimpleHTTP module contained just about everything, with little organization, and no real differentiation between the external API and the library internals. In Happstack 6, SimpleHTTP has been refactored into numerous, smaller modules. The internals have been moved into Happstack.Server.Internal.* so that they are not leaking into the external API. This should make it much easier to find what you are looking for, and prevent you from accidently running across internal things like the WebT monad, which you do not really need to know anything about. Better Documentation -------------------- The API documentation for happstack-server is also much better. All external API functions should now have good haddock documentation with many inline examples. However, learning a new library by studying the API documentation can still be pretty frustrating. So we also have the brand new Happstack Crash Course. http://happstack.com/docs/crashcourse/index.html. The Happstack Crash Course covers a vast majority of the happstack- server API. It covers the API in a logical manner and includes many downloadable, runnable examples. It is intended to be read start to finish, and to also be usable as a reference guide for specific "How do I do XXX" questions. Additionally, the guestbook example has been updated to a cleaner, more modern style of Happstack coding. It also has more comments/ haddock documentation. Better API ---------- During the process of documenting Happstack, many small improvements where made to the API. Once you try to document something stupid you realize how stupid it is and decided it would be good to fix it first ;) For example, the Cookie API now makes it more obvious how to create session cookies vs persistent cookies. And makes it obvious how to expire a cookie. The functions for looking up values in the query string and require body no longer require the use of the RqData monad. You can use the look* functions directly in the ServerPart monad. If you do choose to use RqData, it now has an Applicative instance which can accummulate and report lookup errors. (http://happstack.blogspot.com/2010/10/is-rqdata-monad-still-needed.html ) There are a bunch of other improvements to request data handling documented here, http://happstack.com/docs/crashcourse/RqData.html. Easier Install -------------- In order to make Happstack easier to install we have removed as many dependencies as possible. happstack-data no longer depends on happstack-util, which makes it easier to install happstack-data or happstack-state with out the rest of the framework. HSP and HStringTemplate support has been moved into *optional* happstack-hsp and happstack-hstringtemplate packages. New Features ------------ Happstack also has a number of new features including: - support for Heist templates (http://happstack.com/docs/crashcourse/Templates.html#helloheist ) - support for Hamlet templates - improved environment for extracting query string and form values (http://happstack.blogspot.com/2010/10/is-rqdata-monad-still-needed.html ) - support for recompilation and reloading of templates in a running server (http://happstack.blogspot.com/2010/10/recompile-your-haskell-based-template… ) - directory browsing when using serveDirectory And numerous other improvements including enhancements to IxSet, file locking, and much more. Bigger, Better Version Number ----------------------------- We have also upgraded our version numbers! We have decided to call this release Happstack 6.0 instead of Happstack 0.6. There are two reasons for this: 1. the amount of changes we are making really do represent a new major release 2. it will make it easier to comply with the Haskell package version policy. Now that Happstack 6 is out, we plan to make more frequent releases. The new version scheme will allow us to talk about the next major release (Happstack 7), but still put out changes to Happstack 6 which change the API (aka, Happstack 6.2, etc). GHC 7 - mostly -------------- Happstack mostly works with GHC 7. Due to some compiler bugs, HSP does not work with GHC 7.0.1. These bugs were reported and are fixed in the upcoming GHC 7.0.2 release. If you are not using the optional happstack-hsp package, then GHC 7 is fine. If you are using happstack- hsp, then you will need to use GHC 6.12, a recent version of GHC from darcs, or wait until GHC 7.0.2 comes out. The Future ========== The current future plan looks like this: Happstack 7 ----------- The next major release of Happstack will be Happstack 7. The primary focus of Happstack 7 will be improving happstack-state (also known as MACID). Big features include: - sharding support - a rewrite of IxSet based on kdtrees with much better RAM and CPU performance - performance testing to show how awesome MACID is - much better documentation and examples - better tools for examining and modifying state in running applications There are also a bunch of lower-level API improvements planned which should make it nicer to use happstack-state. Happstack 8 ----------- Happstack 8 will finally feature an enumerator-based HTTP backend. This is a feature we have been hoping to add since January of 2009. http://code.google.com/p/happstack/issues/detail?id=29 Rather than develop a competing HTTP backend, Happstack will put its efforts into improving an existing HTTP backend. We currently have our eye on WAI/warp. However, we will also consider snap and hyena when the time comes. It should be noted that the current lazy I/O based backend is not the relentless nightmare of space leaks that some people might lead you to believe it is. The current happstack-server can easily handle uploads and downloads of large or streaming files with out leaks. But, enumerators *are* nice. How You can Help ================ You are encouraged to get involved in Happstack. The easiest way to get involved is to complain about how horrible Happstack is. If you don't voice your complaints, then we might not know something things to be fixed. If you are looking to make code contributions, please feel free to ask on #happs or the mailing list. There are tasks that are easy for novices, tasks that are worthy of a Ph.D, and everything in between. If you want to work, we can certainly find a way to use your talents! There are also plenty of non-coding related tasks including documentation, graphic design, user surveys, etc. You are also encouraged to blog about your Happstack projects! Thanks! - jeremy shaw

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Application context?
by Petter Egesund 17 Feb '11

17 Feb '11

Hi and thanks for writing such cool software! I am wondering about how to deal with a problem which is releated to what is called application-context in some other web-frameworks. The problem is like this: 1) I would like to do some calculations and put the results in a judy-table (or a regular hash-table) 2) I would like to serve results from this calculations in yesod. So how do I pass my hash as a parameter to functions which is serving content? I was thinking about changing the yesod-code and copy some of the handling from sessions and/or databasehandlers, but it did not seem right - I do not want to maintain my own branch. Is there a better way to do this? Cheers, Petter

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[Hamlet] CSS size wrapper
by Dmitry Kurochkin 17 Feb '11

17 Feb '11

Hi Yesod developers. Attached are two modules to implement CSS size wrappers for Hamlet. It implements several types for different CSS units: * em - EmSize * ex - ExSize * px - PixelSize * % - PercentageSize * cm, in, mm, pc, pt - AbsoluteSize You can create them using an mkSize Template Haskell function, e.g. let size = $(mkSize "100%") All types are instances of Show, Eq, Ord, Num, Fractional and ToCss. This allows you to do math and interpolate it to Hamlet. Ideally, I wanted to have only one type and make an implicit conversion from string literals. But I do not know how to forbid mixing of incompatible units in math (e.g. 10px + 10cm) with a single type. And I do not know how to make implicit conversion from string literals with multiple types. I would appreciate any comments. Including on naming style, type design, API and overall usefulness. Keep in mind that this is the first time I use Template Haskell, so the code may be not optimal and plain ugly (e.g. can we use quasi quotes instead of directly messing with TH?) BTW Michael, one more thing I miss in Hamlet is defining variables in templates. I would prefer to put simple CSS-related constants directly in Cassius instead of a dedicated module. Is it possible to implement? Regards, Dmitry

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Examples and/or tutorials for WAI
by Thomas Sutton 15 Feb '11

15 Feb '11

Hi All, I spent a few hours last night trying to hook a HaXR XML-RPC server up with WAI instead of using the built-in CGI support. Alas, I failed dismally. Is there any more thorough tutorial-style documentation for WAI? Or a good example project that does something more sophisticated than "Hello, Web!"? What tripped me up was trying to figure out the enumerator part of the API so that I can read the request body (and turn it into a String) and run the XML-RPC request handler. Any help would be appreciated! Cheers, Thomas Sutton

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Yesod/WAI and multipart/form-data encoded post requests
by Max Cantor 14 Feb '11

14 Feb '11

Are there any issues with handling multi-part/form-data encoded POST request? Here are my request headers: headers: [("Host","192.168.0.187:6000"),("User-Agent","Consumer-iOS-Phonegap/1.0 CFNetwork/485.12.7 Darwin/10.4.0"),("Content-Length","618"),("Content-Type","multipart/form-data; boundary=BEGINBOUNDARYooooeflkscdlksjlkwrglk238sd723987sdiii"),("Accept","*/*"),("Accept-Language","en-us"),("Accept-Encoding","gzip, deflate"),("Cookie","_SESSION=TZsUfNyzruNnYeETdR/BB2Y/7ns5KRUVMgRkEkghOAo2lXbZ709DsPhclsOndiFmyEttOw5FHCfzW+MVM/eIfJQEruHeE3oFeSrrfdlmSEiZq3H7x+fPOyejZPq0Sd5x"),("Connection","keep-alive")] And what WAI gives back as the params: ("geoLong","103.83032\r\nBEGINBOUNDARYooooeflkscdlksjlkwrglk238sd723987sdiii\r\nContent-Disposition: form-data; name=\"geoLat\"\r\nContent-Type: text/plain\r\n\r\n1.296149\r\nBEGINBOUNDARYooooeflkscdlksjlkwrglk238sd723987sdiii\r\nContent-Disposition: form-data; name=\"geoAccuracy\"\r\nContent-Type: text/plain\r\n\r\n65\r\nBEGINBOUNDARYooooeflkscdlksjlkwrglk238sd723987sdiii\r\nContent-Disposition: form-data; name=\"scannedTime\"\r\nContent-Type: text/plain\r\n\r\n1297677177.991\r\r\nBEGINBOUNDARYooooeflkscdlksjlkwrglk238sd723987sdiii--") Note that the entire request body is treated as one value to the first param instead of being broken up into multiple params. As an HTTP newbie, Its probable that I'm constructing the HTTP request wrong but I dont see what i'm doing wrong. Any help would be greatly appreciated. Max

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