The Open Source Zone

Io is small prototype-based programming language. The ideas in Io are mostly inspired by Smalltalk (all values are objects), Self, NewtonScript and Act1 (prototype-based differential inheritance, actors and futures for concurrency), LISP (code is a runtime inspectable/modifiable tree) and Lua (small, embeddable).

Features

open source BSD license
pure object language
small VM (~10K lines)
small memory footprint (between 64K-200K depending on the platform)
reasonably fast (comparable to Python, Perl, Ruby)
incremental garbage collector, weak links supported
differential prototype-based object model
dynamic typing
exceptions
ANSI C implementation (except for use of inlines and a few lines of coroutine code)
embeddable multi-state (multiple independent VMs can run in the same application)
actor-based concurrency using coroutines/light weight threads
64 bit clean