May 2011 - web-devel - Haskell.org

Fwd: Devel Server
by Mister Asafe Ribeiro 04 May '11

04 May '11

---------- Forwarded message ---------- From: Mister Asafe Ribeiro <asafe.hai.kai(a)gmail.com> Date: Mon, May 2, 2011 at 8:00 PM Subject: Re: [web-devel] Devel Server To: Michael Snoyman <michael(a)snoyman.com> What now ? I get that: Couldn't match expected type `Database.Persist.Base.EntityDef' with actual type `persistent-0.4.2:Database.Persist.Base.EntityD When I change the imports to Database.Persist.TH and Database.Persist.Base the file where is the foundation, KafeeZeit.hs, does not work anymore and I do not know what type/functions supply. I'm using Yesod 0.7 On Sun, May 1, 2011 at 11:57 PM, Michael Snoyman <michael(a)snoyman.com>wrote: > On Mon, May 2, 2011 at 5:53 AM, Mister Asafe Ribeiro > <asafe.hai.kai(a)gmail.com> wrote: > > When I try to run devel server of my yesod powered site i get: > > > > Could not find module `Database.Persist.TH': > > It is a member of the hidden package `persistent-0.4.2'. > > It is a member of the hidden package `persistent-0.3.1.3'. > > Use -v to see a list of the files searched for. > > > > What should I do to expose persistent module ? > > > > Actually, it's now part of persistent-template, try installing that > package. > > Michael > -- na-na-na-na-na-na-na-na-na-na-na-na-na-na-na-na-na-na-na-na-na-na-na-na-na-na-na-na -- na-na-na-na-na-na-na-na-na-na-na-na-na-na-na-na-na-na-na-na-na-na-na-na-na-na-na-na

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Re: [web-devel] wai-handler-dev not finding Yesod
by Amitava Shee 04 May '11

04 May '11

cabal update followed by cabal upgrade yesod did it for me. Thanks. Amitava On Wed, May 4, 2011 at 3:06 PM, Amitava Shee <amitava.shee(a)gmail.com> wrote: > I have cabal installed yesod already and the app runs fine with runhaskell. > I get the error only when invoked via wai-handler-devel. > > -Amitava > > > On Wed, May 4, 2011 at 2:45 PM, Grant Weyburne <weyburne(a)gmail.com> wrote: > >> Hi Amitava, >> >> In case you are missing the yesod module. >> >> cabal install yesod >> >> (some small changes to get this to work with wai developer and yesod >= 7) >> >> Grant >> >> {-# LANGUAGE TypeFamilies, QuasiQuotes, MultiParamTypeClasses, >> TemplateHaskell, OverloadedStrings #-} >> >> module HelloWorld where >> >> import Yesod >> >> data HelloWorld = HelloWorld >> >> mkYesod "HelloWorld" [parseRoutes| >> / HomeR GET >> |] >> >> instance Yesod HelloWorld where >> approot _ = "" >> >> getHomeR = defaultLayout [hamlet|Hello World!|] >> >> withHelloWorld f = toWaiApp HelloWorld >>= f >> >> main = warpDebug 3000 HelloWorld >> >> >> >> >> 2011/5/4 Amitava Shee <amitava.shee(a)gmail.com> >> >>> I am reading the yesod book - http://www.yesodweb.com/book/basics >>> >>> Can someone help me resolve the following issue? >>> >>> amitava$ wai-handler-devel 3000 HelloWorld withHelloWorld >>> Attempting to interpret your app... >>> Compile failed: >>> >>> Could not find module `Yesod': >>> Use -v to see a list of the files searched for. >>> >>> Furthermore, the -v option is not recognized by wai-handler-dev. I am >>> assuming this is a message from the underlying compiler. How do I pass >>> compiler/interpreter flags from wai-devel-handler? >>> >>> Thanks & Regards, >>> Amitava Shee >>> >>> There are two ways of constructing a software design. One is to make it >>> so simple that there are obviously no deficiencies; the other is to make it >>> so complicated that there are no obvious deficiencies. The first method is >>> far more difficult. >>> -- C. A. R. Hoare The Emperor's Old Clothes, CACM February 1981 >>> >>> _______________________________________________ >>> web-devel mailing list >>> web-devel(a)haskell.org >>> http://www.haskell.org/mailman/listinfo/web-devel >>> >>> >> > > > -- > Amitava Shee > Software Architect > > > There are two ways of constructing a software design. One is to make it so > simple that there are obviously no deficiencies; the other is to make it so > complicated that there are no obvious deficiencies. The first method is far > more difficult. > -- C. A. R. Hoare The Emperor's Old Clothes, CACM February 1981 > -- Amitava Shee Software Architect There are two ways of constructing a software design. One is to make it so simple that there are obviously no deficiencies; the other is to make it so complicated that there are no obvious deficiencies. The first method is far more difficult. -- C. A. R. Hoare The Emperor's Old Clothes, CACM February 1981

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wai-handler-dev not finding Yesod
by Amitava Shee 04 May '11

04 May '11

I am reading the yesod book - http://www.yesodweb.com/book/basics Can someone help me resolve the following issue? amitava$ wai-handler-devel 3000 HelloWorld withHelloWorld Attempting to interpret your app... Compile failed: Could not find module `Yesod': Use -v to see a list of the files searched for. Furthermore, the -v option is not recognized by wai-handler-dev. I am assuming this is a message from the underlying compiler. How do I pass compiler/interpreter flags from wai-devel-handler? Thanks & Regards, Amitava Shee There are two ways of constructing a software design. One is to make it so simple that there are obviously no deficiencies; the other is to make it so complicated that there are no obvious deficiencies. The first method is far more difficult. -- C. A. R. Hoare The Emperor's Old Clothes, CACM February 1981

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widgets vs hamlet was Re: on the necessity of extractBody
by Max Cantor 04 May '11

04 May '11

oops, forgot to reply to all ---------------------------- addWidget doesn't work. when I replace addHamlet with addWidget and ^{form} with ^{formW} I get the errors below. Its not that I'm that bothered by having to write extractBody, but since you say I dont have to I feel like this means I'm doing something. Again, I feel like I can get widgets and hamlet and html to work, but I feel like I'm hacking it and dont really understand whats going on. when you say polymorphic hamlet is going away, what will replace it? everything is a widget then? S4M/Server/Handler/Admin.hs:49:11: No instance for (Eq (Route master0)) arising from a use of `widgetToPageContent' Possible fix: add an instance declaration for (Eq (Route master0)) In the expression: widgetToPageContent In a stmt of a 'do' expression: pc <- widgetToPageContent $ do { addWidget ($(Settings.hamletFile "admin/purch-dtl")) } In a stmt of a 'do' expression: (_, formW, et, nonce) <- runFormPost (purchFormlet purch ocrRefs) S4M/Server/Handler/Admin.hs:51:19: The lambda expression `\ render[aCFb] -> hamlet-0.8.0:Text.Hamlet.Debug.unsafeRenderTemplate "hamlet/admin/purch-dtl.hamlet" ... render[aCFb]' has one argument, but its type `GGWidget master0 (GHandler sub0 master0) ()' has none In the expression: \ render[aCFb] -> hamlet-0.8.0:Text.Hamlet.Debug.unsafeRenderTemplate "hamlet/admin/purch-dtl.hamlet" [(["mPsiPkv"], Text.Hamlet.RT.HDMaybe (fmap (\ _var[aCFc] -> ...) mPsiPkv)), (["act"], Text.Hamlet.RT.HDUrl act), ....] render[aCFb] In the result of the splice: $(Settings.hamletFile "admin/purch-dtl") To see what the splice expanded to, use -ddump-splices In the first argument of `addWidget', namely `$(Settings.hamletFile "admin/purch-dtl")' S4M/Server/Handler/Admin.hs:51:19: The lambda expression `\ render[aCKe] -> hamlet-0.8.0:Text.Hamlet.Debug.unsafeRenderTemplate "hamlet/admin/purch-dtl.hamlet" ... render[aCKe]' has one argument, but its type `GGWidget master0 (GHandler sub0 master0) ()' has none In the expression: \ render[aCKe] -> hamlet-0.8.0:Text.Hamlet.Debug.unsafeRenderTemplate "hamlet/admin/purch-dtl.hamlet" [(["mPsiPkv"], Text.Hamlet.RT.HDMaybe (fmap (\ _var[aCKf] -> ...) mPsiPkv)), (["act"], Text.Hamlet.RT.HDUrl act), ....] render[aCKe] In the result of the splice: $(Settings.hamletFile "admin/purch-dtl") To see what the splice expanded to, use -ddump-splices In the first argument of `addWidget', namely `$(Settings.hamletFile "admin/purch-dtl")' On May 4, 2011, at 1:15 PM, Michael Snoyman wrote: > Firstly, polymorphic Hamlet is going the way of the do-do. (Sorry > everyone, the train ride worked out differently than expected, so the > blog post explaining this isn't ready yet.) So going forward these > things should be less of a problem. > > I think the reason you're running into trouble is the use of > "addHamlet"; try replacing it with "addWidget" and see what happens. > > On Tue, May 3, 2011 at 4:33 PM, Max Cantor <mxcantor(a)gmail.com> wrote: >> I've heard that its unnecessary, but I can't seem to get out it of my code. for instance, here is a simple route which should return a small HTML snippet for AJAX requests: >> >> getAdmPurchDetailRh :: EncPurchId -> Handler RepHtml >> getAdmPurchDetailRh epid = withEncPersistKey epid $ \(purchId, purch) -> do >> -- purchImgData <- runDB $ selectList [] [] 50 offset >> -- _TODO this will be done FOR EACH Purchase. need to cache the OcrRefs >> ocrRefs <- map snd <$> runDB ( selectList [] [] 50 0) >> mPsiPkv <- runDB (getBy $ PurchImgUnq purchId True) >> (_, formW, et, nonce) <- runFormPost (purchFormlet purch ocrRefs) >> let act = AdminRb >> pc <- widgetToPageContent $ do >> form <- extractBody formW >> addHamlet $(Settings.hamletFile "admin/purch-dtl") >> hamletToRepHtml [$hamlet|\^{pageBody pc}|] >> >> and the hamlet file: >> >> <div> >> $maybe psiPkv <- mPsiPkv >> <img src=@{getPurchImgRoute psiPkv}> >> $nothing >> <span .missingRecptImage> >> missing image >> <form action=@{act} enctype=#{et}> >> #{nonce} >> ^{form} >> <input type=submit> >> >> if I drop the extractBody formW call and replace ^{form} with ^{formW} it fails to compile. >> >> also, is there a way to get rid of the widgetToPageContent call and then extracting it with pageBody pc? hamletToRepHtml fails when the hamlet references any widgets it seems. >> >> sidenote, i understand that there is alot of polymorphism going on here but I'm still not exactly clear on what i "should" be doing in terms of hamlet, widgets, snippets etc. any style hints are appreciated. >> >> max >> >> >> _______________________________________________ >> web-devel mailing list >> web-devel(a)haskell.org >> http://www.haskell.org/mailman/listinfo/web-devel >>

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on the necessity of extractBody
by Max Cantor 04 May '11

04 May '11

I've heard that its unnecessary, but I can't seem to get out it of my code. for instance, here is a simple route which should return a small HTML snippet for AJAX requests: getAdmPurchDetailRh :: EncPurchId -> Handler RepHtml getAdmPurchDetailRh epid = withEncPersistKey epid $ \(purchId, purch) -> do -- purchImgData <- runDB $ selectList [] [] 50 offset -- _TODO this will be done FOR EACH Purchase. need to cache the OcrRefs ocrRefs <- map snd <$> runDB ( selectList [] [] 50 0) mPsiPkv <- runDB (getBy $ PurchImgUnq purchId True) (_, formW, et, nonce) <- runFormPost (purchFormlet purch ocrRefs) let act = AdminRb pc <- widgetToPageContent $ do form <- extractBody formW addHamlet $(Settings.hamletFile "admin/purch-dtl") hamletToRepHtml [$hamlet|\^{pageBody pc}|] and the hamlet file: <div> $maybe psiPkv <- mPsiPkv <img src=@{getPurchImgRoute psiPkv}> $nothing <span .missingRecptImage> missing image <form action=@{act} enctype=#{et}> #{nonce} ^{form} <input type=submit> if I drop the extractBody formW call and replace ^{form} with ^{formW} it fails to compile. also, is there a way to get rid of the widgetToPageContent call and then extracting it with pageBody pc? hamletToRepHtml fails when the hamlet references any widgets it seems. sidenote, i understand that there is alot of polymorphism going on here but I'm still not exactly clear on what i "should" be doing in terms of hamlet, widgets, snippets etc. any style hints are appreciated. max

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Odd "Ambiguous type variable `a0' in the constraint:" error (with Yesod)
by Mathew de Detrich 02 May '11

02 May '11

Ok so I have a problem that was described here ( http://permalink.gmane.org/gmane.comp.lang.haskell.web/1431) in regards to returning a "Ambiguous type variable `a0' in the constraint error" when compiling. Originally I thought it was due to the way I was coding that part of the code (or to be more accurate the code specifically for creating the so called widgets with addHTML/addWidget,addHamlet). So I copied the example code given here exactly (http://www.yesodweb.com/book/example-widgets) Compiling this worked fine, so at the next point I changed the definition of getRootR to getRootR = defaultLayout $ wrapper $ do setTitle "Polymorphic Hamlet" addHtml [$hamlet|<p>I was added with addHtml|] addHamlet [$hamlet|<p>I was added with addHamlet|] addWidget [$hamlet|<p>I was added with addWidget|] and then to getRootR = defaultLayout $ do setTitle "Polymorphic Hamlet" addHtml [$hamlet|<p>I was added with addHtml|] addHamlet [$hamlet|<p>I was added with addHamlet|] addWidget [$hamlet|<p>I was added with addWidget|] Both times compiled fine, so the issue wasn't what I originally thought that it was (as described in http://permalink.gmane.org/gmane.comp.lang.haskell.web/1431) The problem is, that when I use the above example code in my WebServer, I get this Ambigious type error when compiling (even though I have set up the route the exact same way). Unfortunatley I can't provide the code for my webserver, since its commercially owned (and it would be pointless because its just renamed variables, but otherwise its the same), so does anyone have any ideas what could possibly cause such an error (such as a missing/extra import or some package or something), or possibly some missing instances? Also sorry for creating another mailing list, but its a different issue then what I thought it was originally (and I also wanted to put it on haskell-cafe since its a more general issue)

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Yesod. twice CSS code
by Anton Cheshkov 02 May '11

02 May '11

Hello Michael. I have noticed that my css files contain all code twice *Handler: * *getApplicationFrameR :: Handler RepHtml* *getApplicationFrameR = do* * defaultLayout $ do* * setTitle "Помогай"* * addJulius $(juliusFile "application")* * addScript JsApiR* * addCassius $(cassiusFile "application-frame")* * addWidget $(widgetFile "application-frame")* * * *Cassius: (application-frame.cassius):* * div#header color: red div#content color: green * *css output from browser:* div#header{color:red}div#content{color:green}div#header{color:red}div# content{color:green}body{font-family:sans-serif} The Lucius behavior is the same. What do i make wrong ? Thanks. -- Best regards, Cheshkov Anton Phone: +7 909 005 18 82 Skype: cheshkov_anton

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[ANN] mysql-simple - your go-to package for talking to MySQL
by Bryan O'Sullivan 01 May '11

01 May '11

Hi, folks - Over the past few days, I've released two MySQL-related packages on Hackage that I think should be pretty useful. The first is mysql-simple: http://hackage.haskell.org/package/mysql-simple This is a mid-level binding to the MySQL client API. I aimed it squarely at being both fast and easy to use, and I'm very pleased with the results so far. - Performance: compared to HDBC-mysql, mysql-simple yields a 60% performance improvement on my real-world application. - Ease of use: compared again to HDBC, my real-world application's DB-specific code shrunk by 50% while achieving the above performance increase. - Type safety: it's intentionally hard to construct SQL queries by string concatenation, but of course I provide some nice safe APIs for formatting queries and converting results. That safety does not come at the expense of performance or expressive bloat, as the above results indicate. Because I know that some people favour interacting with their databases via a model such as iteratees, the mysql-simple library is built on top of a very lightweight library. That lower-level library is named mysql: http://hackage.haskell.org/package/mysql This is a low-level binding to the MySQL client API. It is aimed at high performance and simplicity, but more specifically for consumption by authors of higher-level database libraries. It is bare enough of features that it doesn't even perform conversion between Haskell and SQL types, but at the same time it uses bytestrings sensibly, cheaply avoids some nasty signal interruption problems with the MySQL client library, and abstracts some of the tiresome details of memory management. It gives a higher-level library complete control over result conversion, how to fetch results, and all that, so you can focus purely on building iteratees and not the lower-level gunk. Enjoy! B.

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Devel Server
by Mister Asafe Ribeiro 01 May '11

01 May '11

When I try to run devel server of my yesod powered site i get: Could not find module `Database.Persist.TH': It is a member of the hidden package `persistent-0.4.2'. It is a member of the hidden package `persistent-0.3.1.3'. Use -v to see a list of the files searched for. What should I do to expose persistent module ?

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FYI utf8-light linker problem .size xxxxxxx does not evaluate to a constant problem - SOLVED
by Max Cantor 01 May '11

01 May '11

if you have this problem (I did on ubuntu 11.04) the solution is to get the source for utf8-light and comment out the -f-via-C and --ghc-option=O3 flags in both the cabal and .hs file. Max

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