defmodule PgRanges do
  @moduledoc """
  PgRanges provides a simple wrapper around `Postgrex.Range` so that you can
  create scheams with range type fields and use the native range type in
  migrations.

      defmodule MyApp.Employee do
        use Ecto.Schema
        alias PgRanges.DateRange

        schema "employees" do
          field :name, :string
          field :employed_dates, DateRange
        end
      end

      defmodule MyApp.Repo.Migrations.CreateEmployees do
        use Ecto.Migration

        def change do
          create table(:employees) do
            add :name, :string
            add :employed_dates, :daterange
          end
        end
      end

  When used in composing queries, you must cast to the PgRange type.

      import Ecto.Query
      alias PgRanges.DateRange
      alias MyApp.Repo

      range = DateRange.new(~D[2018-11-01], ~D[2019-01-01])

      Repo.all(
        from e in Employee,
        where: fragment("? @> ?", e.employed_dates, type(^range, DateRange))
      )
  """
end