[Haskell-cafe] Bits and pieces needed to build a web server

Jason Dagit dagit at eecs.oregonstate.edu
Thu Aug 3 12:04:07 EDT 2006

On 8/3/06, Johan Tibell <johan.tibell at gmail.com> wrote:
> I've got an idea for a web server model I would like to try and since
> I'm quite new to Haskell it would be great if someone could enumerate
> a couple of useful libraries to me.
> Here's what I need (I've put what I've found so far inside parenthesis):
> * Parsing of incoming HTTP request and creation of replies
> (http://www.haskell.org/http/)

I can't comment here.

> * XML parsing and generating (http://www.cs.york.ac.uk/fp/HaXml/)

I've been using HaXml lately and I'm not real excited about the code
generated by dtd2haskell. I have a large schema and I found it
unweildy to work with the generated types. I wish it generated all of
its data types using record syntax plus generating minimal
instantiation functions.  I guess there are two things I could try to
make this nicer.   1) I could add these features (record syntax w/all
data types & minimal constructors) 2) try creating instances by
parsing xml fragments instead of using the data constructors directly.
 I haven't used the other features much, yet.  Hopefully they are
nice.  HaXml is not your only option in the xml department:


I've heard the arrows interface with HXmlToolbox is very nice.

> * Database support (mainly SQLite but perhaps also MySQL/PostgreSQL)
> (There seems to be several options for this one. I don't know the
> names of the table nor the columns at compile time so I need something
> that doesn't require that.)

I had the same requirement about tables/columns recently and after
trying out several database libraries I found HDBC to handle that
fairly nicely. One of the features I like is that you can choose lazy
queries if you like.  This is very nice for manipulating large
datasets.  I'm not sure if it has drivers for SQLite/MySQL/PostgreSQL
but hopefully yes.


> A big plus if the library is still being developed/maintained.

I can't tell if HXmlToolkit is more active than HaXml.  HDBC does seem
to have some activity, at least recently, although the website appears
to be down most of the time.


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