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Hamido-san's solution

to Space Age in the Clojure Track

Published at Apr 15 2021 · 0 comments
Instructions
Test suite
Solution

Given an age in seconds, calculate how old someone would be on:

  • Earth: orbital period 365.25 Earth days, or 31557600 seconds
  • Mercury: orbital period 0.2408467 Earth years
  • Venus: orbital period 0.61519726 Earth years
  • Mars: orbital period 1.8808158 Earth years
  • Jupiter: orbital period 11.862615 Earth years
  • Saturn: orbital period 29.447498 Earth years
  • Uranus: orbital period 84.016846 Earth years
  • Neptune: orbital period 164.79132 Earth years

So if you were told someone were 1,000,000,000 seconds old, you should be able to say that they're 31.69 Earth-years old.

If you're wondering why Pluto didn't make the cut, go watch this youtube video.

Source

Partially inspired by Chapter 1 in Chris Pine's online Learn to Program tutorial. http://pine.fm/LearnToProgram/?Chapter=01

Submitting Incomplete Solutions

It's possible to submit an incomplete solution so you can see how others have completed the exercise.

space_age_test.clj

(ns space-age-test
  (:require [clojure.test :refer [deftest is]]
            space-age))

(defn- rounds-to
  [expected actual]
  (is (= (Math/round (* 100.0 expected))
         (Math/round (* 100.0 actual)))))

(deftest age-in-earth-years
  (rounds-to 31.69 (space-age/on-earth 1000000000)))

(deftest age-in-mercury-years
  (let [seconds 2134835688]
    (rounds-to 67.65 (space-age/on-earth seconds))
    (rounds-to 280.88 (space-age/on-mercury seconds))))

(deftest age-in-venus-years
  (let [seconds 189839836]
    (rounds-to 6.02 (space-age/on-earth seconds))
    (rounds-to 9.78 (space-age/on-venus seconds))))

(deftest age-on-mars
  (let [seconds 2329871239]
    (rounds-to 73.83 (space-age/on-earth seconds))
    (rounds-to 39.25 (space-age/on-mars seconds))))

(deftest age-on-jupiter
  (let [seconds 901876382]
    (rounds-to 28.58 (space-age/on-earth seconds))
    (rounds-to 2.41 (space-age/on-jupiter seconds))))

(deftest age-on-saturn
  (let [seconds 3000000000]
    (rounds-to 95.06 (space-age/on-earth seconds))
    (rounds-to 3.23 (space-age/on-saturn seconds))))

(deftest age-on-uranus
  (let [seconds 3210123456]
    (rounds-to 101.72 (space-age/on-earth seconds))
    (rounds-to 1.21 (space-age/on-uranus seconds))))

(deftest age-on-neptune
  (let [seconds 8210123456]
    (rounds-to 260.16 (space-age/on-earth seconds))
    (rounds-to 1.58 (space-age/on-neptune seconds))))
(ns space-age)

(def sec/earth-year (* 60 60 24 365.25))

(defn- space-age [ratio sec]
  (/ sec sec/earth-year ratio))

(def on-mercury (partial space-age 0.2408467))
(def on-venus   (partial space-age 0.61519726))
(def on-earth   (partial space-age 1))
(def on-mars    (partial space-age 1.8808158))
(def on-jupiter (partial space-age 11.862615))
(def on-saturn  (partial space-age 29.447498))
(def on-uranus  (partial space-age 84.016846))
(def on-neptune (partial space-age 164.79132))

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