MapReduce Example

(defn nutrition [food]
  (rest (assocl food
    '((hamburger (calories 80) (fat 8)
                 (protein 20))
      (bun (calories 200) (carbs 40) (protein 8)
           (fiber 4))
      (cheese (calories 100) (fat 15) (sodium 150))
      (lettuce (calories 10) (fiber 2))
      (tomato (calories 20) (fiber 2))
      (mayo (calories 40) (fat 5) (sodium 20)) ) )))

>(nutrition 'bun)

((calories 200) (carbs 40) (protein 8) (fiber 4))

>(mapreduce nutrition + '(hamburger bun cheese
                          lettuce tomato mayo))

((sodium 170) (protein 28) (fiber 8) (fat 28)
 (carbs 40) (calories 450))