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hyphenrf's solution

to Space Age in the OCaml Track

Published at May 02 2020 · 0 comments
Test suite

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.

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


(* space-age - 1.2.0 *)
open Base
open OUnit2
open Space_age

let ae ~delta:delta exp got _ctxt =
  let msg = Printf.sprintf "Expected %f got %f, difference is greater than %f"
      exp got delta in
  assert_bool msg (cmp_float ~epsilon:delta exp got)

let tests = [
  "age on Earth" >::
  ae ~delta:0.05 31.69 (age_on Earth 1000000000);
  "age on Mercury" >::
  ae ~delta:0.05 280.88 (age_on Mercury 2134835688);
  "age on Venus" >::
  ae ~delta:0.05 9.78 (age_on Venus 189839836);
  "age on Mars" >::
  ae ~delta:0.05 35.88 (age_on Mars 2129871239);
  "age on Jupiter" >::
  ae ~delta:0.05 2.41 (age_on Jupiter 901876382);
  "age on Saturn" >::
  ae ~delta:0.05 2.15 (age_on Saturn 2000000000);
  "age on Uranus" >::
  ae ~delta:0.05 0.46 (age_on Uranus 1210123456);
  "age on Neptune" >::
  ae ~delta:0.05 0.35 (age_on Neptune 1821023456);

let () =
  run_test_tt_main ("space-age tests" >::: tests)
type planet = Mercury | Venus | Earth | Mars
            | Jupiter | Saturn | Neptune | Uranus

let age_on spacerock secs =
  let ey = float secs /. 31557600. in
  match spacerock with
      | Earth   -> ey           | Jupiter -> ey/.11.862615
      | Mercury -> ey/.0.240846 | Saturn  -> ey/.29.447498
      | Venus   -> ey/.0.615197 | Neptune -> ey/.164.79132
      | Mars    -> ey/.1.880815 | Uranus  -> ey/.84.016846

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