Dylan is the "Write anything, do everything" language: from
scripting and prototyping to robust application and component
development. Dylan can be customized to support targeted
domains such as games and business-to-business Internet
solutions. These customizations can support non-programmers
(e.g. scripting) while allowing a gentle slope to complex
programs of several hundred thousand lines of code. The
transition from one to the other occurs smoothly, without
drastic breaks. No other mainstream languages have this
capability.
There's also a free software implementation of Dylan
that runs on Linux: Gwydion Dylan.