Add space-age exercise (#152)

config.json

@@ -585,6 +585,19 @@
         ],
         "difficulty": 2
       },
+      {
+        "slug": "space-age",
+        "name": "Space Age",
+        "uuid": "f43676b5-ab9c-4cc8-9159-a30401deaa29",
+        "practices": [
+          "floating-point-numbers"
+        ],
+        "prerequisites": [
+          "numbers",
+          "floating-point-numbers"
+        ],
+        "difficulty": 2
+      },
       {
         "slug": "collatz-conjecture",
         "name": "Collatz Conjecture",

exercises/practice/space-age/.docs/instructions.md

@@ -0,0 +1,25 @@
+# Instructions
+
+Given an age in seconds, calculate how old someone would be on:
+
+- Mercury: orbital period 0.2408467 Earth years
+- Venus: orbital period 0.61519726 Earth years
+- Earth: orbital period 1.0 Earth years, 365.25 Earth days, or 31557600 seconds
+- 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][pluto-video].
+
+Note: The actual length of one complete orbit of the Earth around the sun is closer to 365.256 days (1 sidereal year).
+The Gregorian calendar has, on average, 365.2425 days.
+While not entirely accurate, 365.25 is the value used in this exercise.
+See [Year on Wikipedia][year] for more ways to measure a year.
+
+[pluto-video]: https://www.youtube.com/watch?v=Z_2gbGXzFbs
+[year]: https://en.wikipedia.org/wiki/Year#Summary

exercises/practice/space-age/.meta/config.json

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "ErikSchierboom"
+  ],
+  "files": {
+    "solution": [
+      "src/space_age.cljs"
+    ],
+    "test": [
+      "test/space_age_test.cljs"
+    ],
+    "example": [
+      ".meta/src/example.cljs"
+    ]
+  },
+  "blurb": "Given an age in seconds, calculate how old someone is in terms of a given planet's solar years.",
+  "source": "Partially inspired by Chapter 1 in Chris Pine's online Learn to Program tutorial.",
+  "source_url": "https://pine.fm/LearnToProgram/?Chapter=01"
+}

exercises/practice/space-age/.meta/src/example.cljs

@@ -0,0 +1,15 @@
+(ns space-age)
+
+(def earth-year-seconds (* 365.25 24 60 60))
+
+(defn- on-planet [seconds orbital-period]
+  (/ seconds earth-year-seconds orbital-period))
+
+(defn on-earth [seconds] (on-planet seconds 1.0))
+(defn on-mercury [seconds] (on-planet seconds 0.2408467))
+(defn on-venus [seconds] (on-planet seconds 0.61519726))
+(defn on-mars [seconds] (on-planet seconds 1.8808158))
+(defn on-jupiter [seconds] (on-planet seconds 11.862615))
+(defn on-saturn [seconds] (on-planet seconds 29.447498))
+(defn on-uranus [seconds] (on-planet seconds 84.016846))
+(defn on-neptune [seconds] (on-planet seconds 164.79132))

exercises/practice/space-age/.meta/tests.toml

@@ -0,0 +1,27 @@
+# This is an auto-generated file. Regular comments will be removed when this
+# file is regenerated. Regenerating will not touch any manually added keys,
+# so comments can be added in a "comment" key.
+
+[84f609af-5a91-4d68-90a3-9e32d8a5cd34]
+description = "age on Earth"
+
+[ca20c4e9-6054-458c-9312-79679ffab40b]
+description = "age on Mercury"
+
+[502c6529-fd1b-41d3-8fab-65e03082b024]
+description = "age on Venus"
+
+[9ceadf5e-a0d5-4388-9d40-2c459227ceb8]
+description = "age on Mars"
+
+[42927dc3-fe5e-4f76-a5b5-f737fc19bcde]
+description = "age on Jupiter"
+
+[8469b332-7837-4ada-b27c-00ee043ebcad]
+description = "age on Saturn"
+
+[999354c1-76f8-4bb5-a672-f317b6436743]
+description = "age on Uranus"
+
+[80096d30-a0d4-4449-903e-a381178355d8]
+description = "age on Neptune"

exercises/practice/space-age/deps.edn

@@ -0,0 +1,10 @@
+{:deps
+ {org.clojure/clojure {:mvn/version "1.10.1"}
+  org.clojure/clojurescript {:mvn/version "1.10.773"}}
+
+ :aliases
+ {:test
+  {:extra-paths ["test"]
+   :extra-deps
+   {olical/cljs-test-runner {:mvn/version "3.8.0"}}
+   :main-opts ["-m" "cljs-test-runner.main"]}}}

exercises/practice/space-age/src/space_age.cljs

@@ -0,0 +1,33 @@
+(ns space-age)
+
+(defn on-mercury [] ;; <- arglist goes here
+  ;; your code goes here
+)
+
+(defn on-venus [] ;; <- arglist goes here
+  ;; your code goes here
+)
+
+(defn on-earth [] ;; <- arglist goes here
+      ;; your code goes here
+)
+
+(defn on-mars [] ;; <- arglist goes here
+  ;; your code goes here
+)
+
+(defn on-jupiter [] ;; <- arglist goes here
+  ;; your code goes here
+)
+
+(defn on-saturn [] ;; <- arglist goes here
+  ;; your code goes here
+)
+
+(defn on-uranus [] ;; <- arglist goes here
+  ;; your code goes here
+)
+
+(defn on-neptune [] ;; <- arglist goes here
+  ;; your code goes here
+)

exercises/practice/space-age/test/space_age_test.cljs

@@ -0,0 +1,46 @@
+(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))))