Since the PLT Scheme community is so helpful, you might consider diving into the language by immediately trying to build that Arc-flavored dialect. The source to everything is available - give it a shot!
I'm trying to avoid the temptation to play with language too much, while I build my startup app.
Theres so much cool stuff there.. Being interested in the language makes for much more pleasant hacking / prototyping experience. [Id lost this feeling with C++/java even ruby]
You can actually just get the basics and then learn in more depth as interest and time dictate.
