A more-or-less-Smalltalk implementation that natively uses the classes of the CocoaFramework on MacOsx.

http://www.fscript.org/

You can embed Fscript in Cocoa applications as a scripting language. Even more cool-ly, you can embed Cocoa applications inside Fscript! This gives you an interpreter with live access to the classes and objects of the Cocoa application.

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CategorySmalltalk