What Haskell web framework would one use for an HTTP/Websocket data and messaging platform?

Question

Just looking at Haskell and web frameworks and wondering if it would make sense to use Haskell's great threading/event functionality to power a platform for writing HTML5 and REST apps that expose an HTTP API for data and a WebSocket (with maybe SockJS support for appropriate fallback) API for events? It doesn't seem like the "big" web frameworks support WebSockets as a first-class citizen, though they seem to have a lot of other things going for them.

My concern is making use of available cores, which Haskell can do well, but also providing easy user integration on the server side for validation and server-side logic (maybe by embedding Lua or similar?). If one wrote this on the JVM, one could make use of multiple server-side language support and lots of libraries for this sort of thing.

I'm sure people are doing things like this in a one-off solution for their own applications but I'm thinking along the lines of a PaaS-type approach where one can write HTML5 apps with data (including proper synchronization for offline use) and eventing "for free" as a fundamental part of the platform. Most logic would reside in the browser but some could be run on the server with the appropriate hooks and a reasonable embeddability (JavaScript seems out of the question and not sure about embedding interpreters in Haskell as I'm only dangerously familiar with Haskell in general).

Part of the problem I've had with Haskell so far is that I'm not a Math guy. I didn't study CS in college and I'm a creative-type thinker. So a lot of the tutorials and documentation get me pretty lost, especially when dealing with the mathematical stuff.

Has anyone trod this path already? Am I late to the party? :)

Answer 1

Gregory Collins gave a tutorial at CUFP last year about using Snap to build an interactive chat website using long polling (not websockets). The source code is here.

In the websockets department, Jasper Van der Jeugt wrote a Haskell websockets library. It is available on hackage and comes with websockets-snap, which provides Snap framework support. There's also wai-websockets which provides integration with Warp.

Answer 2

I believe all of the major frameworks have some level of websockets support, so they should all be a fair choice based on your requirements. For Yesod, there's an example of creating a chat system (using eventsource, not websockets) available in the book:

http://www.yesodweb.com/book/wiki-chat-example