Fleshed out the UI a little. Added a "literal" button that replaces the operator panel with a literal panel. Added the navigation buttons, but they're not functional yet.

#{
	main <- {
		foo <- :n {
			if: n < 10 {
				true
			} else: {
				foo <- :n { n }
			}
			foo: n + 1
		}
		print: (string: (foo: 0))
	}
}