[Haskell-cafe] Where to start about writing web/HTTP apps ?

[gary ng]

Thanks for the info. Looking forward to see it. What I
would like to see is also some form of templating
system like HTMLTemplate in Python, that is reading in
HTML then merge in data using the DOM model, on the
server(may be the XML package in haskell already does
it). As for AJAX, I would assume that once there is
built-in support for HTTP, it is just a matter of
handling XMLRPC/JSONRPC calls from the client, instead
of HTTP calls, that should be solved automatically by
then, given the extremely strong parser support in
haskell.

--- Brian McQueen <mcqueenorama at gmail.com> wrote:

> I emailed the WASH guy the other day and he is
> currently working on
> integrating it with a web server.  There is talk
> about Haskell server
> pages.  It sounds quite interesting.  I'm impressed
> with WASH as it
> is, though.  I too am hoping to see it when it moves
> from a plain CGI
> model to the something that's built right into the
> server.  There are
> some very useful and intersting features such as the
> way you program
> as if it were a resident server, rather than a
> remote, swtateless exec
> and restart CGI.  I like the way handlers for the
> input fields are
> integrated with the definition of the field, as well
> as with the error
> handling for the field.  I saw something about
> caching of the static
> portion of the pages too.
> 
> I'd like to see some means of integrating the new,
> and quite awesome
> AJAX techniques too.
> 
> Brian McQueen
> 
> On 9/10/05, Thomas Spriggs
> <thomasspriggs at hotmail.com> wrote:
> > >From: gary ng <garyng2000 at yahoo.com>
> > >To: haskell-cafe at haskell.org
> > >Subject: [Haskell-cafe] Where to start about
> writing web/HTTP apps ?
> > >Date: Sat, 10 Sep 2005 04:15:45 -0700 (PDT)
> > >
> > >Hi,
> > Hi,
> > >
> > >I just start learning haskell and have to say
> that it
> > >is stunning in how precise it can be(coming from
> a
> > >background of C then python/perl/js).
> > >
> > >I want to write apps for WEB and have briefly
> read
> > >WASH. However, that seems to be a CGI based
> solution.
> > >What I want is a native HTTP server(written in
> > >haskell), like Twisted/Cherrypy in Python. Are
> there
> > >any boilerplate(I know I should scrap the
> boilerplate
> > >but I need to have something to get start) for
> > >reference ?
> > >
> > >In addition, during my learning process, I keep
> on
> > >using my old experience as reference such as
> writing
> > >simple programs that needs functions like
> > >ltrim/rtrim/substr etc. that is in almost any
> language
> > >I have used. But it seems that haskell doesn't
> have
> > >it. I know that a haskell expert can write them
> in no
> > >time with things like dropWhile and reverse, it
> is a
> > >bit frustrating for new comers from a imperative
> > >background.
> > >
> > >Oh, while I am still here, I am reading "The
> Evolution
> > >of a Haskell Programmer"
> >
>
>http://www.willamette.edu/~fruehr/haskell/evolution.html
> > >
> > >and learning the various way to tackle the same
> > >problem. Obviously, there are lots of things I
> don't
> > >know what it is about and I would tackle them as
> time
> > >go by. But I have problem even with the seems to
> be
> > >simple one like this :
> > I don't think its that simple.
> > >
> > >fac n = foldr (\x g n -> g (x*n)) id [1..n] 1
> > >
> > >I can understand a foldl or foldr version but
> have
> > >problem with this, especially the "id" and the
> > The id is the identity function defined
> > id x = x
> > >trailing "1" and the function being folded takes
> 3
> > >parameters instead of 2(as in standard
> foldr/foldl
> > >solution).
> > >
> > For a start the previous standard fold solutions
> take 3 parameters not 2.
> > Its just the "fac n = foldr (\x g n -> g (x*n)) id
> [1..n] 1" example appears
> > to take 4. However it doesn't, foldr always takes
> 3 arguments.
> > foldr :: (a -> b -> b) -> b -> [a] -> b (from zvon
> reference)
> > In fact the foldr function actually returns a
> function in this case. It
> > could be rewritten as
> > fac n = (foldr (\x g n -> g (x*n)) id [1..n]) 1
> > with the additional brackets added for clarity.
> > 
> > >Would appreciate if someone can knock on my head
> and
> > >tell me what is going on in it.
> > Well, here goes. The way the lambda function/foldr
> thing evaluates, the
> > resulting foldl like function needs a new identity
> parameter hence the
> > additional "1". To demonstrate something like how
> this is evaluated for a
> > low number eg 3: (Please would someone correct me
> if I have made a mistake
> > in this)
> > fac 3 = (foldr (\x g n -> g (x*n)) id [1..3]) 1
> > fac 3 = (foldr (\x g n -> g (x*n)) id [1,2,3]) 1
> > fac 3 = (foldr (\x g n -> g (x*n)) (\n -> id
> (3*n)) [1,2])) 1
> > fac 3 = (foldr (\x g n -> g (x*n)) (\n -> (\n ->
> id (3*n)) (2*n)) [1]) 1
> > fac 3 = (foldr (\x g n -> g (x*n)) (\n -> (\n ->
> (\n -> id (3*n)) (2*n))
> > (1*n)) []) 1
> > fac 3 = (\n -> (\n -> (\n -> id (3*n)) (2*n))
> (1*n)) 1
> > fac 3 = (\n -> (\n -> id (3*n)) (2*n)) (1*1)
> > fac 3 = (\n -> (\n -> id (3*n)) (2*n)) 1
> > fac 3 = (\n -> id (3*n)) (2*1)
> > fac 3 = (\n -> id (3*n)) 2
> > fac 3 = id (3*2)
> > fac 3 = id 6
> > fac 3 = 6
> > I would suggest that you use something other than
> the "evolution of a
> > haskell programmer" to learn haskell as the
> versions of factorial get
> > complicated very quickly and its largely use less
> as you should probably
> > just use:
> > fac n = product [1..n]
> > anyway. A better introduction would be something
> like
> > http://www.cse.unsw.edu.au/~cs1011/05s2/ and use
> >
>
http://zvon.org/other/haskell/Outputglobal/index.html
> and
> > http://www.haskell.org/tutorial/ if you want to
> learn something in specific
> > or are strugling. All links from
> http://www.haskell.org/learning.html of
> > course.
> > >
> > >thanks for help in advance.
> > You're welcome.
> > >
> > >regards,
> > >
> > >gary
> > >
> > >
> > >
> > >
> >
>
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> > 
> > Well good luck furthering your knowledge of
> haskell,
> > 
> > Thomas
> > 
> >
>
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