text: * Profile guided typing
    http://www.cs.umd.edu/~davidan/papers/druby-tr-4935.pdf
  * proc/lambda
  * Exceptions (raise/rescue)
  * Struct
  * callcc
  * Recursive customization
  * Integrate document server
  * Scanf type inference
  * Performance tuning
    * CPU usage
    * Memory footprint
    * Cloning template
    * Cut branches
    * Statistics
  * stubs load-path
  