- web-devel - Haskell.org

ALPHA: http-types 0.1
by Aristid Breitkreuz 06 Feb '11

06 Feb '11

Hi, I just wanted to announce that I uploaded a first version of http-types to hackage: http://hackage.haskell.org/package/http-types-0.1 This version is very much an Alpha version. And, uh, do give feedback: I promise that I will keep myself better in check, this time. Aristid

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multiple user interface languages
by Alberto G. Corona 04 Feb '11

04 Feb '11

Are there any high level, efficient, transparent way to handle multilanguage appkications? (I mean UI languages, that is languages that people use to communicate) There are many "dirty" ways to handle it . But none are satisfactory. Either to.. 1) Store the string in a database and perform inefficient queries to compose the page (optionally with caching). The user interface code is not particulary elegant. 2) Store the string and string constants in a separate module for each language. It is as efficient at it can be. but not particularly elegant. 3) Create multiple pages, one fo each language It is.fast at rumtime, but at the cost of duplication of the embedded code, o it is not very maintainable. Time ago i used the option 2 for my first Haskell web application, So every page had at the botton a runtime asignation of the language strings used in the page: (yesvar, novar)=case lang of "es" -> (LangEs.yes, LangEs.no) _ -> (LangEn.yes, LangEn.no) For yes/no strings I don´t like it. Any other alternative?

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Timing WAI response generation
by Neil Mitchell 04 Feb '11

04 Feb '11

Hi, I've ported Hoogle to WAI/Warp and it's great - I am very happy. The only feature I lost is the ability to time how long a response takes to generate/send. For my purposes, I'm not even overly bothered whether it's the time taken to generate, or the time taken to send to the clients machine, or something somewhere between these two times. I came up with a couple of ideas: 1) I generate my response with a lazy byte string. I could make the final chunk of the lazy bytestring something impure (with unsafePerformIO) that writes into an MVar when it gets forced. 2) If I knew more about enumerators/iteratees I think it might be possible for each chunk generated to start a time, wait til the chunk is ready, and then stop the timer - giving the exact time to generate all the chunks. Or append two chunks, one at each end, that start/stop the timer. Does anyone have any better suggestions, or ways of performing the timing? Thanks, Neil

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Re: [web-devel] ALPHA: http-types 0.1
by Aristid Breitkreuz 04 Feb '11

04 Feb '11

Writing this from my phone, so I'll be brief. I'm OK with the name CIByteString, I just thought the Http would clarify that this is not safe for different encodings. But I can change this. Parsing/rendering sounds like a good idea. I will probably use different function names, but you can set up aliases in wai-extra, right? Headers are already there, no? You're confusing me. Thanks for the nice feedback! Aristid "sent from my Android" Am 04.02.2011 07:09 schrieb "Michael Snoyman" <michael(a)snoyman.com>: Alright, everything seems fine to me. Some more comments: * Besides the fact that I think HttpCIByteString is too verbose, it presents another problem: I cannot transparently switch over to it in WAI and http-enumerator. If you kept the same name (CIByteString), I could simply switch over to your version without any breaking changes. * I like methodGet et al. * Do you want to consider some parsing functions? I can provide you the code. Some things I would imagine would be: * parseQueryString :: ByteString -> [(ByteString, Maybe ByteString)] (I'm not sure if in practice anyone cares about the Maybe btw, but you are right that it is more theoretically correct) * renderQueryString :: [(ByteString, Maybe ByteString)] -> ByteString * parsePath :: ByteString -> [String], which would do all splitting-on-slash, percent decoding and UTF-8 decoding * renderPath :: [String] -> ByteString, which would be the reverse of parsePath * renderPathQuery :: [String] -> [(ByteString, ByteString)] -> ByteString * parseHttpAccept :: ByteString -> [ByteString] * Are you planning on adding headers as well? Basically, feel free to raid Network.Wai.Parse[1]. [1] http://hackage.haskell.org/packages/archive/wai-extra/0.3.1/doc/html/Networ… On Fri, Feb 4, 2011 at 12:23 AM, Aristid Breitkreuz <aristidb(a)googlemail.com> wrote: > OK, I uploaded a fixed version: > http://hackage.haskell.org/pack...

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Re: [web-devel] Proposal: http-types
by Michael Snoyman 04 Feb '11

04 Feb '11

2011/2/3 kyra <kyrab(a)mail.ru>: > On 2/2/2011 1:32 PM, Michael Snoyman wrote: >> >> * Request/response header key. In WAI, I use data CIByteString = >> CIByteString !ByteString !ByteString, one version being the lowercase, >> the other the original. > > I'm using Microsoft kernel-mode http server (http.sys). They have "known > headers" enumeration and "unknown headers" string. Now, while http.sys > parses requests and gives me enum keys for "known headers" I have to unparse > them back strings to adapt them to WAI. It's not too much critical, but I > would prefer the header key to be an ADT. > > Cheers, Kyra. > Do you mean you're implementing a WAI handler on top of http.sys? That's cool, would you consider releasing it on Hackage? I think the header key especially would be a bad fit for an ADT: there are *far* too many standard ones to really include all of them, and much more than request methods, new ones are made up. Just look at all the special handling in http-types for the request methods, and imagine writing those extra lines for *every* supported header. Michael

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[Yesod] how to write PersistFIeld instance?
by Katsutoshi Itoh 03 Feb '11

03 Feb '11

I'd like to introduce serializable data type like this: data Role = Teacher | Student deriving (Read, Show, Eq, Ord) share2 mkPersist (mkMigrate "migrateAll") [$persist| User ident String : : role Role Maybe Update : |] instance PersistField Role where ??? Would you teach me how to write this instance?

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Proposal: http-types
by Aristid Breitkreuz 03 Feb '11

03 Feb '11

Hi, Hear me out, I have an idea! :-) How about creating a new package "http-types" containing Request / Response / status code / header name types for HTTP. These could be used by both server and client software, and might even allow switching between HTTP client libraries (say, if I want to switch between http-enumerator and HTTP). What do you think? Aristid

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On creating a navigation menu in yesod
by Rafael Cunha de Almeida 03 Feb '11

03 Feb '11

Hello, I'm trying to create a navigation menu in yesod. First I thought about creating a widget. But, afaik, I'd need to add it in each handler of the site, after all, the menu should be always visible. So I ditched that approach. I wrote the menu code right in default-layout.hamlet. I wrote a loop that iterates over menuRoutes, which is a list of tuples composed of route and the menu name for that route. Like this: menuRoutes = [(RootR, "Home"), (TeamR, "Team")] During the iteration I add each of those. I created that in Site.hs, right after mkYesodData. The problem with that approach is that the link for the current site should be disabled. So, if we're at RootR, then there should be a <b>Home</b> in the menu instead of <a href="/">Home</a>. That's where I got stuck. I can't really pass anything to defaultLayout when I'm at the handler function and there doesn't seem to be the information of which handler was executed to create the current view. I thought the information could be in the Foundation (via getYesod), but I couldn't find anything. What's the recommended way of creating such menus? []'s Rafael

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[Wai] Sending partial files
by Bardur Arantsson 03 Feb '11

03 Feb '11

Hi all, Is there a way to send a part of a file in response to a request using WAI? I'm assuming it's possible, but I'm having a little trouble figuring out the type signatures in Network.Wai. I think I'll be able to adapt the Data.Enumerator.Binary.enumFile and enumHandle functions to handle a range, so I guess the question is really: How can I send a status + headers + arbitrary output from an enumerator in WAI? Cheers,

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Re: [web-devel] [Haskell-cafe] http-enumerator: redirects, streaming and keep-alive
by Michael Snoyman 03 Feb '11

03 Feb '11

On Thu, Feb 3, 2011 at 12:00 AM, Antoine Latter <aslatter(a)gmail.com> wrote: > On Wed, Feb 2, 2011 at 3:01 PM, Felipe Almeida Lessa > <felipe.lessa(a)gmail.com> wrote: >> On Wed, Feb 2, 2011 at 6:30 PM, Antoine Latter <aslatter(a)gmail.com> wrote: >>> Or you could remove the socket from the map while it's in use. >> >> And what about connection limits? We shouldn't create a thousand >> connections to the same host =). >> > > Not a bad idea, but that may be creeping outside the scope of the bug > as reported. > > If you're writing a web-scraper/spider, it is true you might need some > sort of higher-level manager to handle concurrent access. I'm not sure > what that would look like, though > >> -- >> Felipe. >> > I think Felipe's point is that using the approach I outlined, we will never spawn more than one connection to a single host. By simply taking the socket out of the map, there's no limit to the number of sockets that will be created. Michael

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