A demonstration of using Haskell as a web socket server.
Accompanying blog post can be found here.
To compile and run the code, you will need a Haskell compiler. To make it simple, you would probably also want a package manager to manage dependencies. The Haskell Platform is a 'batteries included' download that contains the GHC compiler, cabal-install (the package manager) and various other libraries and tools.
Once installed, the code can be compiled and run with the following commands:
cabal install --dependencies-only
cabal run
To run the client, just open stock-ticker.html in a web browser that supports WebSockets.
(I've only tested this Ubuntu 14.04 and with GHC 7.8.3 although it should compile on other OSs with other versions of GHC).