I would like to know opinions about the fastest combination of language, libraries and tools that allow for fast prototyping of application in the 3 most important OS (Win, Mac, Linux).
In the past, I've used processing for visual sketches, but I would like to know about other options, since this is oriented to visual artists, not programmer professionals.
Thanks!
LispWorks is quite useful for that. It has versions for Win/Mac/Linux and much of the code is platform independent - including threads, networking, database access, graphics. It implements an extended version of Common Lisp and thus comes with all the necessary tools for incremental and interactive software development. It can also generate applications for delivery. Primetrader is an example of an application that runs mostly unchanged on all three platforms. You can download the application from the Netfonds site and try it out. Ken Dickey describes using LispWorks and Extreme Programming: Extremely Successful Software.
Common Lisp gets much of its development speed due to the incremental and interactive development style that is possible. Many facilities of the language are optimized for that. For example the Common Lisp Object System (CLOS) allows you to change objects at runtime, or even change the object system itself at runtime. Classes can be added/remove/changed. Methods can be added/removed/changed. Objects can change their class and will be automatically updated for class updates. This allows you to modify/extend complex object-oriented software while it is running. The traditional cycle of edit/compile/deloy/initialize/debug of applications is gone. Instead you work with the application and extend/replace parts of it without stopping it.