[Haskell-cafe] happstack file serving

Antoine Latter aslatter at gmail.com
Tue Nov 1 15:58:41 CET 2011

Hi Gary,

A convention I use in my top-level handler is:

simpleHTTP nullConf $
          [ <dynamic content handler>
          , serveDirectory DisableBrowsing [] "static"
          , <404 handler>

where 'serveDirectory' is a function that ships with happstack-server
and serves up the contents of a directory which it is pointed at. I
then keep all of my static CSS and Javascript files in the static

The second argument to 'serveDirectory' is used to specify the
index-files to look for in a folder if the user browses to a static
folder, so here you could specify "index.html" to have
'serveDirectory' look for files named "index.html" and serve them up
when a top-level folder is requested.


On Tue, Nov 1, 2011 at 9:48 AM, Gary Klindt <gary.klindt at googlemail.com> wrote:
> Hello all,
> I want to have a web application using one 'index.html' file with ajax
> requests and a happstack web server which response to server requests.
> For that purpose I need to use some javascript libraries in my directory
> tree. I tried:
> main = simpleHTTP nullConf $ msum [ serveFile (asContentType "text/html")
> "index.html"
>                                  , serveFile (asContentType
> "text/javascript") "javascript/js.js" ]
> The js.js - file will never be found in this way because after finding the
> index.html,
> the msum function stops (as described in the happstack crash course).
> If I change the order, I can see the source of js.js.
> I also tried leaving it.
> In every case, inside index.html a function defined in js.js cannot be
> called.
> (naturally, I sourced the file inside index.html)
> Is it possible to obtain the effect of beeing able to call a function in an
> external file
> without jmacro?
> I also tried:
> main = simpleHTTP nullConf $ msum [ dir "ok" $ ok "jeah!"
>                                  , serveFile (asContentType "text/html")
> "index.html"
> Couldn't match expected type `[Char]' with actual type `Response'
>    Expected type: ServerPartT IO [Char]
>      Actual type: ServerPartT IO Response
>    In the return type of a call of `serveFile'
>    In the expression:
>      serveFile (asContentType "text/html") "index.html"
> The webserver should take requests, and if there is none (no dir, personal
> convention), it should provide index.html.
> The error is because msum needs the same input types. Is it possible to
> transform one of these types to the other?
> It seems that my approach to the problem is not the right one, the one the
> authors thought about while programming.
> I wanted to have a clear seperation from logic (haskell) and interface
> (javascript). Is it right that using a running
> haskell webserver with the web application 'in it' is in general a faster
> solution than using for example apache with
> the fcgi module?
> Which approach would you prefer to realize such an ajax application?
> Greets Gary
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