F-Script: Lightweight open-source scripting layer for Cocoa This sounds really cool... The tool comes with a interactive command-line shell for manipulating objects, an object browser that lets you graphically find, explore, and manipulate objects, and powerful tools for inspecting objects by querying core data, Cocoa arrays, and more. As the site says, this sounds like a really good way to learn Cocoa from the inside, by reverse-engineering existing apps. The site has tons of resources on F-Script and related projects, which are based on Smalltalk.