Add space-age exercise

config.json

@@ -472,6 +472,14 @@
           "strings"
         ]
       },
+      {
+        "slug": "space-age",
+        "name": "Space Age",
+        "uuid": "d2bd28fb-489a-43bf-929c-2a6c6a60ef17",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 1
+      },
       {
         "slug": "darts",
         "name": "Darts",

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": [
+    "BNAndras"
+  ],
+  "files": {
+    "solution": [
+      "space-age.rkt"
+    ],
+    "test": [
+      "space-age-test.rkt"
+    ],
+    "example": [
+      ".meta/example.rkt"
+    ]
+  },
+  "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/example.rkt

@@ -0,0 +1,30 @@
+#lang racket
+
+(provide on-mercury
+         on-venus
+         on-earth
+         on-mars
+         on-jupiter
+         on-saturn
+         on-uranus
+         on-neptune)
+
+(define-values (earth-seconds) 31557600)
+
+(define (get-local-age seconds ratio) (/ seconds (* earth-seconds ratio)))
+
+(define (on-mercury seconds) (get-local-age seconds 0.2408467))
+
+(define (on-venus seconds) (get-local-age seconds 0.61519726))
+
+(define (on-earth seconds) (get-local-age seconds 1))
+
+(define (on-mars seconds) (get-local-age seconds 1.8808158))
+
+(define (on-jupiter seconds) (get-local-age seconds 11.862615))
+
+(define (on-saturn seconds) (get-local-age seconds 29.447498))
+
+(define (on-uranus seconds) (get-local-age seconds 84.016846))
+
+(define (on-neptune seconds) (get-local-age seconds 164.79132))

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

@@ -0,0 +1,38 @@
+# This is an auto-generated file.
+#
+# Regenerating this file via `configlet sync` will:
+# - Recreate every `description` key/value pair
+# - Recreate every `reimplements` key/value pair, where they exist in problem-specifications
+# - Remove any `include = true` key/value pair (an omitted `include` key implies inclusion)
+# - Preserve any other key/value pair
+#
+# As user-added comments (using the # character) will be removed when this file
+# is regenerated, comments can be added via 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"
+
+[57b96e2a-1178-40b7-b34d-f3c9c34e4bf4]
+description = "invalid planet causes error"
+include = false

exercises/practice/space-age/space-age-test.rkt

@@ -0,0 +1,52 @@
+#lang racket
+
+(require "space-age.rkt")
+
+(module+ test
+  (require rackunit rackunit/text-ui)
+
+  (define suite
+    (test-suite
+      "space-age tests"
+
+      (test-= "age on Earth"
+              (on-earth 1000000000)
+              31.69
+              0.01)
+
+      (test-= "age on Mercury"
+              (on-mercury 2134835688)
+              280.88
+              0.01)
+
+      (test-= "age on Venus"
+              (on-venus 189839836)
+              9.78
+              0.01)
+
+      (test-= "age on Mars"
+              (on-mars 2129871239)
+              35.88
+              0.01)
+
+     (test-= "age on Jupiter"
+             (on-jupiter 901876382)
+             2.41
+             0.01)
+
+     (test-= "age on Saturn"
+             (on-saturn 2000000000)
+             2.15
+             0.01)
+
+     (test-= "age on Uranus"
+             (on-uranus 1210123456)
+             0.46
+             0.01)
+
+     (test-= "age on Neptune"
+             (on-neptune 1821023456)
+             0.35
+             0.01)))
+
+ (run-tests suite))

exercises/practice/space-age/space-age.rkt

@@ -0,0 +1,10 @@
+#lang racket
+
+(provide on-mercury
+         on-venus
+         on-earth
+         on-mars
+         on-jupiter
+         on-saturn
+         on-uranus
+         on-neptune)