If you would like to get a feel for the programming model and experiment with the API without installing anything, take a look at our interactive River Trail shell. The shell runs in any current version of Firefox, Chrome, and Safari. However, the code you write in the shell will be executed sequentially using a library implementation and you won't see any speedup.
However if you are running Firefox and you have installed the River Trail browser extension for Firefox (see below on how), your code will run in parallel.
You need to install our Firefox extension to use our prototype compiler that enables execution of River Trail on parallel hardware. You can download a pre-built version compatible with Firefox 33+ for Windows, Mac OS X and Linux. (An archive of all versions of the extension can be found here.)
If you would like to build the extension yourself, we have written a README that explains the process.
It is possible to use River Trail with various OpenCL platforms and devices. In particular, it's possiblet to run River Trail applications on a supported GPU. Not all device kinds on all platforms are supported; once you have the extension and OpenCL installed, take a look at the extension's device selection settings to check whether your configuration is supported.
Once you have the extension installed and working, take a look at our demos:
For a first impression, you can watch this video, as well, or head over to InfoQ for an introductory talk recorded at Strange Loop 2012. For a interesting discussion of various problems we are trying to solve, you can view this interview, which discusses our approach and objectives.
A word of caution: River Trail is a prototype and the extension is not yet meant for use on the public web. Please uninstall or disable the extension when surfing the web and use it only for web pages you trust.
The API described in the wiki reflects what the River Trail prototype implements. Some design choices, such as, for instance, the use of extra arguments, are dictated by limitations of what our implementation approach (i.e., as a browser extension) allows.