gistfile1.clj

(def ^:dynamic *start-time* (System/nanoTime))

(defn elapsed-ms
  []
  (/ (- (System/nanoTime) *start-time*) 1000000))

(defn ^double position-offset-angle
  ([]
   (position-offset-angle 5000))
  ([^long duration]
   (position-offset-angle duration (/ (* Math/PI 2.0) duration)))
  ([^long duration ^double scale]
   (* (mod (elapsed-ms) duration) scale)))

;; This code will not compile:
;; https://gist.github.com/aamedina/3ccee6bac03c04be8d2a
(let [theta (position-offset-angle)
      x-offset (* (Math/cos theta) 0.5)
      y-offset (* (Math/sin theta) 0.5)])

;; This will compile successfully
(let [theta (position-offset-angle)] theta)

;; However any let binding which references the theta local will also throw:
;; https://gist.github.com/aamedina/f86d059d16e9cf27b567
(let [theta (position-offset-angle)
      x-offset theta])

;; The following also throws the same exception as above:
(let [theta (position-offset-angle)]
  (* 5 theta))