May 2011 - web-devel - Haskell.org

http-enumerator connecting via a http proxy
by Erik de Castro Lopo 25 Jun '11

25 Jun '11

Hi all, Has anyone managed to get http-enumerator connecting via a http proxy? I've tried constructing a custom 'Request m' object and submitting that the httpLbsRedirect but all I've managed to get is: connect: does not exist (Connection refused) Clues? Would this need a new http-enumerator function something like: httpProxyLbsRedirect :: (MonadIO m, Failure HttpException m) => String -> Int -> Request m -> Manager -> m Response where the first two parameters are the proxy hostname and port? Cheers, Erik -- ---------------------------------------------------------------------- Erik de Castro Lopo http://www.mega-nerd.com/

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Kick-off discussion: Yesod 0.9
by Michael Snoyman 01 Jun '11

01 Jun '11

Hi all, It's been about a month since the 0.8 release of Yesod. In the release announcement[1], we laid out some goals. Let's take a chance to analyze where we're at: * Documentation: Still improving as always. In particular, the new Yesod site is making it much easier for me to write new content (I have a few things on my local system that can finally go up). * Static file caching headers: Implemented by Greg Weber. We'll likely be making some API changes to handle embedded files, though that discussion deserves its own blog post. * Other template types: For Hamlet 0.9, we're going to be splitting Julius/Coffeescript into their own package, and juggling the type signature for Coffeescript a bit. At that point, it should be straightforward to embed Coffeescript directly into a Yesod app, just like Julius is today. * Something like require.js: This is something we haven't started on yet. I'll likely start looking into it this week. Additionally, I know that a lot of my sites (jQuery powered) have numerous onload calls per page; I think we can try to make that more efficient as well. I would especially like people's input on this point. * i18n: The solution is written, and I'm using it in production. At this point, I'd call it beta quality, and I'd appreciate input. * Forms package: It's been rewritten, but hasn't really had much input from others. Now's the time to speak up if you have any opinions on it. The code is available on Hackage. * Embedded objects in MongoDB: No work done yet. * Performance improvements: Nothing in particular. If you have any examples of Yesod performing badly, please let us know. The goal is for Yesod 0.9 to be feature complete, and for 1.0 to be a fairly stable API. From the list above, my two priorities are better Javascript loading (require.js) and static file serving. However, there's one other major issue we need to address: the devel server. Unfortunately, it doesn't work very well at all right now. Thankfully, "yesod build" *does* work very well, and for my development I've fallen back to simply "yesod build && ./dist/build/myapp/myapp" on the command line. My guess is that we're 90% of the way there on "yesod devel". This is a project that isn't tightly bound to the rest of the API work, and would be very approachable for someone trying to get started on Yesod development. If you're interested in helping out here, please let me know. I have no specific timeframe in mind for Yesod 0.9. As it stands now, it looks like the 0.9 release will involve almost no API breakage, which is a very good sign. But if you have any ideas you'd like to contribute, I'd recommend getting them in in the next week or two. Michael [1] http://www.yesodweb.com/blog/2011/4/announcing-yesod-0-8

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Re: [web-devel] DTD types
by John Millikin 31 May '11

31 May '11

On Tue, May 31, 2011 at 00:30, Yitzchak Gale <gale(a)sefer.org> wrote: >>> For example, I couldn't use name, because for DTD namespaces >>> *are* significant so they need a different Eq instance. I ended up >>> just using Text." > >> I don't understand what this means; the xml-types Eq instance >> for Name compares both the namespace and local name > > Ah, OK. I misunderstood the docs - it says that the "prefix" > is not used in the Eq instance, so I took that to mean > that namespaces prefixes were not used. Now that I look > more carefully at the code itself, I see that is not true. > > But then what is a "prefix"? The IsString instance always sets > the prefix to Nothing. I've scoured the XML spec and not > found anything it could possibly represent. What have I > missed? Lets say you have a document like this: <foo:doc xmlns:foo="http://my/namespace/here">bar</foo:doc> The name of the element will have the components: prefix = "foo" namespace = "http://my/namespace/here" local name = "doc" The prefix is not semantically important; all names are identified by the (namespace, local name) pair. Thus, comparing two names ignores the prefix. But it's still useful to keep around when 1) working with poorly-written parsers (eg, many XMPP servers) or 2) performing minimal-diff changes on a complex document. > Another point I noticed when looking at the IsString instance > for Name: it can introduce crashes into a program if someone > accidentally puts a '{' at the beginning of a Name string. > Everywhere else, your code is safe; even if someone inserts > invalid XML, you leave it up to the application to decide > how much to validate and what to do if validation fails. > > So could you please change this to pass the string through > as a plain Name without a namespace if Clark notation > parsing fails? Thanks. The IsString instance is intended for overloaded string literals -- that is, the source code would look something like this: ------------------ elem = Element "{http://my/namespace/here}doc" [] [] ------------------ It's not intended for parsing arbitrary input, as it performs no validation of its input (aside from trivial checks for Clark brackets). If you are concerned that a developer may cause exceptions by writing incorrect code, it would be better to use the Name constructor directly. > I noticed that you did not send your response to the list. > Do you mind if I forward a copy of this response > to the web-devel list? Oops, didn't realize there were two separate email threads. Here's the text of my earlier email, for future readers: ---------------- On Mon, May 30, 2011 at 11:13, John Millikin <jmillikin(a)gmail.com> wrote: > I agree that it makes more sense as a separate package -- DTDs are > sort of a layer on top of XML, and there's lots of people who want to > work with one without worrying about the other. I don't mind merging > them if you want, but separate seems better. > >> For example, I couldn't use name, because for DTD namespaces *are* significant so they >> need a different Eq instance. I ended up just using Text." > > I don't understand what this means; the xml-types Eq instance for Name > compares both the namespace and local name: > > -------------------------------- > instance Eq Name where > (==) = (==) `on` (\x -> (nameNamespace x, nameLocalName x)) > -------------------------------- > > As to the package itself, I have only one suggestion: can you add a > constructor to DTDComponent for processing instructions? If I'm > reading the XML spec correctly, these can occur anywhere within a DTD. > > Thank you very much for the good work! ----------------

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Re: [web-devel] Kick-off discussion: Yesod 0.9
by Aristid Breitkreuz 31 May '11

31 May '11

Am 31.05.2011 09:12 schrieb "Michael Snoyman" <michael(a)snoyman.com>: > > I think Aristid's aws > package[1] in particular would be good for the S3 backend. > Except currently only SimpleDB actually works. Is your XML cursor stuff ready soon? Because that's one of the reasons why I paused development. AWS involves a lot of XML and I felt that my current combination of xml + xml-monad (two packages) is not optimal or even just future-proof. > Michael > > [1] http://hackage.haskell.org/package/aws > > _______________________________________________ > web-devel mailing list > web-devel(a)haskell.org > http://www.haskell.org/mailman/listinfo/web-devel

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Raw POST data
by Jeremy Hughes 31 May '11

31 May '11

Hi again, I can't find a means to access raw POST data. Both Network.Wai.Request and Yesod.Request.Request appear to only contain pre-parsed values. What am I missing? J

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yesod in five minutes
by George Colpitts 30 May '11

30 May '11

Hi I tried yesod in five minutes <http://www.yesodweb.com/five-minutes> and I'm having a problem trying to add a date and time string that would update on refresh. I just want to add it to the simple page you get with yesod in 5 minutes. I can embed a date and time string that is the value of a Haskell variable but that won't refresh on update to the current date and time. My simplistic approach was to put a line in Handler/root.hs: currTimeAndDate = getClockTime but that won't compile: Handler/Root.hs:22:21: No instance for (blaze-html-0.4.1.1:Text.Blaze.ToHtml (IO ClockTime)) arising from a use of `toHtml' Possible fix: add an instance declaration for (blaze-html-0.4.1.1:Text.Blaze.ToHtml (IO ClockTime)) In the second argument of `(.)', namely `toHtml' In the expression: hamlet-0.8.2:Text.Hamlet.Quasi.htmlToHamletMonad . toHtml In a stmt of a 'do' expression: (hamlet-0.8.2:Text.Hamlet.Quasi.htmlToHamletMonad . toHtml) currTimeAndDate I'm sure it would compile if I wrapped getClockTime with unsafePerformIO to get a String but then refresh of the page wouldn't give me the current time. In addition it doesn't seem like the right way to do this. I'm sure my problem is due to my lack of knowledge of Haskell IO and monads which I do plan to learn thoroughly but right now I'd just like to get this to work. It seems like I could do it with a form in Yesod but that seems like overkill and wouldn't have the look I want. I'm very impressed with the software, the book and the source code for the www.haskellers.com. It is a testimony to the quality of all three that I have got this far, particularly considering how little I know. Any help would be greatly appreciated. Sincerely George

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Using Hamlet for a static website
by Neil Mitchell 30 May '11

30 May '11

Hi, My website at http://community.haskell.org/~ndm/ is based on lots of template files, for example: http://community.haskell.org/~ndm/darcs/website/pages/catch.html (not a real HTML file, but a partial HTML file). These files all start with some metadata, and then have some templated language below, which gets combined with headers/footers to produce my website. I did this all using custom code, but I'd like to move to using Hamlet with YAML, so I can throw away lots of my custom code and so I get lots of additional features I'm currently missing because I have to hand-roll the framework myself. I couldn't find any examples of anything else doing this, so two questions: 1) I couldn't find any easy way to say "run hamlet on each of the files in this directory"? Will I have to do a getDirectoryContents in IO, lift that into Q, and then statically call hamletFile on a list? Then I'll output the HTML to file. 2) Is there an existing example of this? Writing a static site in terms of Hamlet seems like a nice idea, and I can't be the first to have thought of it. Thanks, Neil

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dtd-types
by Yitzchak Gale 30 May '11

30 May '11

I've released a preliminary version of the dtd-types package: http://projects.haskell.org/dtd/ I originally intended these types to be eventually incorporated into John's xml-types package. However, after writing them, I now see that there is actually very little in common. The feel of a DTD is quite different than XML itself. The only type from xml-types that I actually used was EntityID, which is a very minor. As John pointed out, it is very unusual to find internal DTD subsets in XML documents in the wild. And I find that my own code involving external DTDs has little to do with my code for XML in practice, even though the two are of course complimentary in purpose. However, if people feel that this shouldn't be a separate package, I'd be happy to deprecate it. Of course, I am eager for any comments and suggestions about the types themselves. Thanks, Yitz

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Multi sites with Yesod or WAI
by Eric Schug 29 May '11

29 May '11

Is it possible to route applications based on the site name so that a single haskell process can support multiple sites with some shared data/applications? Is this handled at the WAI level or within Yesod? Eric

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Yesod proxy
by Jeremy Hughes 29 May '11

29 May '11

Hi all, The app I'm writing uses a private file store accessible by HTTP (rackspace's cloud files). Some of what the app does is authenticate access to files in the store, a kind of selective proxy (or alternatively, like a static handler that can fetch http:// as well as file://). Before I go ahead and write a simple proxying function using http-enumerator &co, does one already exist in Yesod? And if not, any pointers on writing one and integrating it with GGHandler and HasReps? Cheers, Jeremy

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