Dear All, Some history: About two or so years ago, before I'd heard of Yesod, we started a web development framework for Haskell which we called Panther. This framework was quite similar to ASP.Net or PHP: pages were source files and it had a pre-processor which generated Haskell code. To cut a long story short: I never really finished off Panther, as I found out about Michael's wonderful Yesod. I'm now resurrecting the project with a different goal: hosting multiple WAI applications over clusters. The fun part of the old Panther was that it used an evolutionary rewiring algorithm to distribute applications over clusters of computers over multiple sites. As you can imagine, that was a great joy to write :) When the newer Panther actually stabilizes (or even works) I'll explain various bits of it in more detail. One of the nice features that Panther had was the ability to specify client-side operations on the server. For example, given the HTML:
<div id="myDiv"> <i>Some Text</i> </div> <input type="text" id="name" /> <button type="button" panther:onclick="changeMyDiv"> Change! </button>
We could replace the text in the <div> with "Other Text", change the style of the <div> and print the contents of the input element with the following Haskell code:
changeMyDiv :: (Monad m) => Element -> Ajax m () changeMyDiv button = do [div, input] <- getElementsById ["myDiv", "name"]
setInnerHtml div "Other Text" setStyle div ["font-weight" =: "bold", "color" =: "green"]
v <- getValue input liftIO $ print v
(the code was actually a little more complex, as 'getElementsById' yielded a list of 'Maybe Element'. But you get the idea). In earlier days - before we adopted Yesod and rewrote everything :) - we found this functionality to be quite useful. We mostly used it to handle dynamic forms, progress reporting and so on. I'd completely forgotten about the panther-ajax package. The past few discussions on web-devel regarding dynamic forms made me think about how we have solved similar problems, and what we used to do in the past. Anyway, last week I decided to port the package over to Yesod and make some improvements to the API. I've put an experimental version on GitHub for those who are at all interested in this: https://github.com/MassiveTactical/panther-ajax There is a simple example in the repo. For those of you who don't want to build the example, but would still like see it working, the example is currently running at: http://meadowstalk.com:3141/ It should still be running... You can get an immediate idea for how it works by examining the network activity in Chrome (or whatever your browser may be). If any of you are interested - or are idly curious and have some spare time - I'd love to hear any feedback. The library still needs a lot of improvement. There is still quite a bit of code to port over, and the optimizing assembler needs some tender loving care before it can be used again. Kind Regards, Blake Rain Massive Tactical