Find elements in given collections by pattern matching, i.e. all attachments in a POST request.

find.ex

defmodule Find do
  @moduledoc """
  Implements methods to find elements in given collections by pattern matching.
  """

  @doc """
  Finds the first element in a list to match a given pattern.
  """
  def first_match(collection) do
    Enum.find(collection, fn(element) ->
      match?({:fruit, _}, element)
    end)
  end

  @doc """
  Finds all the elements in a list that match a given pattern.
  """
  def all_matches(collection) do
    Enum.filter(collection, fn(element) ->
      match?({:fruit, _}, element)
    end)
  end
  
  @doc """
  Finds all attachments in POST request.
  """
  def find_attachments(params) do
    Enum.filter(params, fn element ->
      match?({_, %Plug.Upload{}}, element)
    end)
    |> Enum.map(fn {_, v} -> v end)
  end
end

# And then, to test the implemented methods:

iex> require Find
iex> array = [{:fruit, "Apple"}, {:vegetable, "Carrot"}, {:fruit, "Orange"}]
iex> Find.first_match(array)
{:fruit, "Apple"}
iex> Find.all_matches(array)
[{:fruit, "Apple"}, {:fruit, "Orange"}]
iex> map = %{fruit: "Apple", vegetable: "Carrot"}
iex> Find.first_match(map)
{:fruit, "Apple"}
iex> Find.all_matches(map)
[{:fruit, "Apple"}]