Correct version of inc! added by sjamaan on Tue Jan 26 14:54:51 2016
(define-syntax inc!
(syntax-rules ()
((_ x)
(set! x (+ x 1)))
((_ x delta)
(set! x (+ x delta)))))(define-syntax inc!
(syntax-rules ()
((_ x)
(set! x (+ x 1)))
((_ x delta)
(set! x (+ x delta)))))