36 lines
1.0 KiB
Elixir
36 lines
1.0 KiB
Elixir
|
defmodule SpaceAge do
|
||
|
|
@type planet ::
|
||
|
|
:mercury
|
||
|
|
| :venus
|
||
|
|
| :earth
|
||
|
|
| :mars
|
||
|
|
| :jupiter
|
||
|
|
| :saturn
|
||
|
|
| :uranus
|
||
|
|
| :neptune
|
||
|
|
|
||
|
|
@planets ~w(mercury venus earth mars jupiter saturn uranus neptune)a
|
||
|
|
|
||
|
|
defguardp is_planet(planet) when planet in @planets
|
||
|
|
|
||
|
|
defp factor(:mercury), do: 0.2408467
|
||
|
|
defp factor(:venus), do: 0.61519726
|
||
|
|
defp factor(:earth), do: 1.0
|
||
|
|
defp factor(:mars), do: 1.8808158
|
||
|
|
defp factor(:jupiter), do: 11.862615
|
||
|
|
defp factor(:saturn), do: 29.447498
|
||
|
|
defp factor(:uranus), do: 84.016846
|
||
|
|
defp factor(:neptune), do: 164.79132
|
||
|
|
|
||
|
|
@doc """
|
||
|
|
Return the number of years a person that has lived for 'seconds' seconds is
|
||
|
|
aged on 'planet', or an error if 'planet' is not a planet.
|
||
|
|
"""
|
||
|
|
@spec age_on(planet, pos_integer) :: {:ok, float} | {:error, String.t()}
|
||
|
|
def age_on(planet, seconds) when is_planet(planet),
|
||
|
|
do: {:ok, seconds / (factor(planet) * 31_557_600)}
|
||
|
|
|
||
|
|
def age_on(_planet, _seconds),
|
||
|
|
do: {:error, "not a planet"}
|
||
|
|
end
|