Heist is a powerful template system that supports both HTML5 and XML.
Some of Heist's features are:

 * Designer-friendly HTML5 (or XML) syntax
 * Templates can be reloaded to make changes visible without recompiling
   your Haskell code
 * Enforces near-perfect separation of business logic
   and view
 * Powerful abstraction primitives allowing you to eliminate repetition
 * Easy creation of domain-specific markup languages
 * Built-in support for including JSON and Markdown content in templates
 * Simple mechanism for designer-specified template caching
 * Optional merging of multiple <head> tags defined anywhere in the document

WWW: http://snapframework.com/
