How to get the struct type in Elixir

So you don’t know what’s the type of struct you’re passing somewhere? Maybe it can be one of few types and you have to distinguish them? Or any other reason… But it’s about checking the struct type. Just use one of the coolest Elixir features - pattern matching!

Check this out:

iex(1)> some_struct = %MyApp.User{}
iex(2)> %type{} = some_struct
iex(3)> type
MyApp.User

That’s just a hook point for a bunch of cool facilities, like function call by module type:

defmodule Chess.Bishop do
  def move(piece), do: move_diagonally(piece)
end

defmodule Chess.Rook do
  def move(piece), do: move_straight(piece)
end

defmodule Chess.Pawn do
  def move(piece), do: move_forward(piece)
end

And then in console:

iex(1)> piece = get_chess_piece()
iex(2)> %module{} = piece
iex(3)> module.move(piece)

Have fun! If you'd like to learn more about structs in Elixir, check this blog post: Elixir Trickery: Cheating on Structs, And Why It Pays Off.