Are there any real-world prototype-based programming languages with a whole development cycle?
"A whole development cycle" like Ruby and Python: web frameworks, scripting/interacting with the system, tools for debugging, profiling, etc.
Thank you
A brief note on PBPLs: (let's call these languages PBPL : prototype-based programming language)
There are some PBPLs out there. Some are being widely used like JavaScript (which Node.js may bring it into the field - or may not!). One other language is ActionScript which is also a PBPL but tightly bound to Flash VM (is it correct to say so?).
From less known ones I can speak of Lua which has a strong reputation in game development (mostly spread by WOW) but never took off as a full language. Lua has a table concept which can provide you some sort of prototype based programming facility.
There is also JScript (Windows scripting tool) which is already pointless by the newcomer PowerShell (I have used JScript to manipulate IIS but I never understood what is JScript!).
Others can be named like io (indeed very very neat, you will fall in love with it; absolutely impossible to use) and REBOL (What is this all about? A proprietary scripting tool? You must be kidding!) and newLISP (Which is actually a full language, but no one ever heard about it).
For sure there are much more to list here but either I do not remember or I did not understood them as a real world thing, like Self).
I did not found one and the only candidate (JavaScript) is still spending very first steps (like Node.js).
Still one other valid candidate would be JavaScript! There is a .NET based implementation named IronJS which is implemented in F# and is going pretty well. This way one can have whole .NET development cycle at his toolbox. It is based on DLR and can be used in both .NET and Mono!