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A dependency-free utility library containing 100+ useful functions.

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moar lib enum.ex
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lib/enum.ex 

defmodule Moar.Enum do

  # @related [test](/test/enum_test.exs)



  @moduledoc "Enum-related functions."



  @doc "Like `Enum.at/3` but raises if `index` is out of bounds."

  @spec at!(Enum.t(), integer() | [integer()], any()) :: any()

  def at!(enum, index, default \\ nil) when is_integer(index) do

    if length(enum) < index + 1,

      do: raise("Out of range: index #{index} of enum with length #{length(enum)}: #{inspect(enum)}"),

      else: Enum.at(enum, index, default)

  end



  @doc "Removes nil elements from `enum`."

  @spec compact(Enum.t()) :: Enum.t()

  def compact(enum),

    do: enum |> Enum.reject(&is_nil(&1))



  @doc "Returns the first item of `enum`, or raises if it is empty."

  @spec first!(Enum.t()) :: any()

  def first!(enum),

    do: Enum.at(enum, 0) || raise("Expected enumerable to have at least one item")



  @doc """

  Returns true if the value is a map or a keyword list.



  This cannot be used as a guard because it uses `Keyword.keyword?` under the hood. Also, because of that,

  it might scan an entire list to see if it's a keyword list, so it might be expensive.

  """

  @spec is_map_or_keyword(any()) :: boolean()

  def is_map_or_keyword(value),

    do: is_map(value) || (is_list(value) && Keyword.keyword?(value))



  @doc "Sorts `enum` case-insensitively. Uses `Enum.sort_by/3` under the hood."

  @spec isort(Enum.t()) :: Enum.t()

  def isort(enum),

    do: enum |> isort_by(&to_string/1)



  @doc "Sorts `enum` case-insensitively by `mapper` function. Uses `Enum.sort_by/3` under the hood."

  @spec isort_by(Enum.t(), (any() -> any())) :: Enum.t()

  def isort_by(enum, mapper),

    do: enum |> Enum.sort_by(&(mapper.(&1) |> String.downcase()))



  @doc """

  Returns a list of elements at the given indices. If `:all` is given instead of a list of indices, the entire

  enum is returned.



  ```elixir

  iex> Moar.Enum.take_at(["A", "B", "C"], [0, 2])

  ["A", "C"]



  iex> Moar.Enum.take_at(["A", "B", "C"], :all)

  ["A", "B", "C"]

  ```

  """

  @spec take_at(Enum.t(), integer() | [integer()] | :all) :: any()

  def take_at(enum, :all), do: enum

  def take_at(enum, list) when is_list(list), do: Enum.map(list, &Enum.at(enum, &1))



  @doc """

  Returns `:tid` fields from `enumerable`.



  This unusual function exists because the authors of Moar use tids (test IDs) extensively in tests.

  """

  @spec tids(Enum.t()) :: list()

  def tids(enumerable),

    do: enumerable |> Enum.map(& &1.tid)

end