Adam Chlipala has written a very nice language and web framework called Ur/Web.
Some impressive things about it:
- SQL and HTML (”XML Fragments”) are built right into the language itself. Forget an end tag? No soup for you!
- Continuation based state management
- Functional Reactive Javascript: “Programs allocate data sources and then describe the page as a pure function of those data sources. When the sources change, the page changes automatically.”
- Very elegant support for meta-programming
- Efficient memory management without using garbage collection
If you’re a fan of functional programming or have a general interest in computer languages I’d encourage you to check it out.