Woo is a fast non-blocking HTTP server built on top of libev. Although Woo is written in Common Lisp, it aims to be the fastest web server written in any programming language.
How fast?
Clack is a web application environment for Common Lisp inspired by Python’s WSGI and Ruby’s Rack.
Example:
(defvar *handler*
(clack:clackup
(lambda (env)
(declare (ignore env))
'(200 (:content-type "text/plain") ("Hello, Clack!")))))