[Haskell-beginners] Having fun with yesod, and a few questions came up.

[Michael Litchard]

Yes, thank you. It would be useful for you to package up a sample
application with a lighttpd config file. I would appreciate that.


On Thu, Jul 15, 2010 at 11:06 AM, Michael Snoyman <michael at snoyman.com> wrote:
> Regarding the incompleteness of fastcgi tutorial: I'm not quite sure what
> you mean. The deploying section[1] gives information on how to configure
> lighttpd to run a compiled Yesod application, *not* on how to write that
> application. The tutorials show you how to write a Yesod application
> The only thing missing now is your other question: which handler to use. The
> answer to wai-handler-fastcgi[2]. It's built on top of the libfcgi C
> library, so you'll need to make sure you have that installed. A previous
> version was built on the direct-fastcgi[3] package, but I found that to have
> considerably lower performance. If people are interested in a
> wai-handler-direct-fastcgi, let me know, I'll release it.
> Anyway, the function you're probably looking for in Yesod is toWaiApp[4],
> which produces an Application. You can then pass that Application to the
> wai-handler-fastcgi run function, and you'll have a fastcgi executable.
> If you think it will be useful, I can package up a sample application with a
> lighttpd config file. And if anyone out there knows how to write config
> files for other servers, that would be a nice addition as well.
> Michael
>
> [1] http://docs.yesodweb.com/yesod/deploying.html
> [2] http://hackage.haskell.org/package/wai-handler-fastcgi
> [3] http://hackage.haskell.org/package/direct-fastcgi
> [4] http://docs.yesodweb.com/haddock/yesod/Yesod-Dispatch.html#v%3AtoWaiApp
>
> On Thu, Jul 15, 2010 at 8:39 PM, Michael Litchard <michael at schmong.org>
> wrote:
>>
>> Okay this is what I have so far, concerning what I need to do on the
>> Haskell end of things to get it working with lighttpd.
>>
>> As an example, I will use blog.lhs from the yesod tutorial
>>
>> All that's left now is the main function. Yesod is built on top of
>> WAI, so you can use any WAI handler you wish. For the tutorials, we'll
>> use the basicHandler that comes built-in with Yesod: it serves content
>> via CGI if the appropriate environment variables are available,
>> otherwise with simpleserver.
>>
>> > main :: IO ()
>> > main = do
>> >   entries <- loadEntries
>> >   basicHandler 3000 $ Blog entries
>>
>> This brings into sharp relief my ignorance on how to use hackage. I
>> tried to investigate hackage looking for some WAI handler that would
>> get me what I want. Namely, turning this example into a fastCGI
>> application that lighttpd could use.
>>
>> So this generates two questions. How would one use hackage to find a
>> WAI handler to use for fastCGI?
>> What would be an example of a WAI handler I could use with yesod?
>>
>> Thanks for making it possible for guys like me to do this.
>>
>> On Thu, Jul 15, 2010 at 9:33 AM, Michael Snoyman <michael at snoyman.com>
>> wrote:
>> >
>> >
>> > On Thu, Jul 15, 2010 at 6:57 PM, Michael Litchard <michael at schmong.org>
>> > wrote:
>> >>
>> >> I'm playing with yesod http://docs.yesodweb.com/yesod/,  and I have a
>> >> few questions:
>> >>
>> >> Here's an excerpt from yesod/tutorial/i18n.lhs
>> >>
>> >> **NOTE: This tutorial requires the development version of Yesod
>> >> (version 0.4.0). The [tutorial main page]($root/yesod/tutorial/) has
>> >> instructions on setting up your environment.**
>> >>
>> >> Where is $root?
>> >> I thought it was where yesod-examples-0.4.0 was installed. But if this
>> >> is the case, I'm not finding these instructions. This makes me think I
>> >> am confused about the directory $root represents.
>> >>
>> > Sorry about the $root stuff, it's an artifact from the web site. I use
>> > the
>> > same code base for the yesod-examples package and the tutorials on the
>> > site
>> > to make sure everything compiles properly. In any event, the line in
>> > question is out-of-date and needs to be removed: 0.4.0 has been
>> > officially
>> > released, so you just need a cabal install yesod to get started.
>> >>
>> >> I was playing around with the code and made some changes. Here is the
>> >> line in question, with the complete code below for context.
>> >>
>> >> > instance Yesod I18N where
>> >> >     approot _ = ""
>> >>
>> >> This does what I expect it to do, it runs the program when I open up
>> >> http://my.blog.server/
>> >>
>> >> however, I wanted to see what would happen if I played around with it
>> >> a little bit. I want the same program to run when I point my browser
>> >> to http://my.blog.server/blog
>> >>
>> >> so I made this change
>> >> >     approot _ = "/blog"
>> >>
>> >> but now when I point my browser to http://my.blog.server/blog it gets
>> >> re-written to http:/my.blog.server/blog/blog
>> >> and then this error message
>> >> Not Found
>> >> /blog/blog
>> >>
>> >> Not sure what is going on here, could someone enlighten me?
>> >>
>> >>
>> > The approot function is used for *rendering* routes. This has no affect
>> > on
>> > where Yesod *listens* to requests. For example, you could put approot _
>> > =
>> > "http://haskell.org", but you wouldn't be able to respond to requests
>> > for
>> > that domain. Nonetheless, URLs generated by Yesod would then point to
>> > haskell.org.
>> > Basically, the only time to get fancy with approot is when you're doing
>> > URL
>> > rewriting for (Fast)CGI hosted applications. When you use a standalone
>> > server, you'll always* be serving from the root of the domain, and so
>> > the
>> > value of approot should just be that domain name.
>> > * Of course, there's always exceptions.
>> > You might look at the documentation[1] where it explains when it's
>> > permissible to use an empty string for the value of approot.
>> > Michael
>> > [1] http://docs.yesodweb.com/haddock/yesod/Yesod-Yesod.html#v%3Aapproot
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