exercism/elixir/lucas-numbers/lib/lucas_numbers.ex

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Elixir
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2024-03-07 12:33:20 +00:00
defmodule LucasNumbers do
@moduledoc """
Lucas numbers are an infinite sequence of numbers which build progressively
which hold a strong correlation to the golden ratio (φ or ϕ)
E.g.: 2, 1, 3, 4, 7, 11, 18, 29, ...
"""
def generate(count) when is_integer(count) and count > 0 do
{2, 1}
|> Stream.iterate(fn {a, b} -> {b, a + b} end)
|> Stream.map(&elem(&1, 0))
|> Enum.take(count)
end
def generate(_count), do: raise(ArgumentError, "count must be specified as an integer >= 1")
end