As far as the Quil window with graphics, I'm not sure if it's because an Applet is being used, but on Mac OS X, the window pops up for me behind my other windows and without focus. I have to hide all of the other windows on top of it to find it. It's weird, I know.
What is the command you're running that gives you the error "quil.Applet cannot be cast to clojure.lang.IFn" ?
You are correct, it works! I am on a Mac and I needed to press F3 (show all windows) to see the graphics window. It does not show up if you just do cmd-Tab.
As for the second error - I was incorrectly trying to run the core.clj, so no problem there.
Thanks for the help! I had fun drawing circles :))
What is the command you're running that gives you the error "quil.Applet cannot be cast to clojure.lang.IFn" ?