Alternately shamelessly repurposing the implementation (uniq_list/3) of Enum.uniq/1:
defmodule Demo do
def duplicates?(list),
do: duplicates?(list, %{})
defp duplicates?([], _) do
false
end
defp duplicates?([head|tail], set) do
case set do
%{^head => true} ->
true
_ ->
duplicates?(tail, Map.put(set, head, true))
end
end
def run(list) do
list
|> duplicates?()
|> inspect()
|> IO.puts()
end
end
list = [1, 2, 3, 3, 2, 1]
uniq_list = Enum.uniq(list)
Demo.run(list) # true
Demo.run(uniq_list) # false
A lot can be learned by scouring through Elixir’s source code. The important thing is to understand how it works.
