String Interpolation With Just About Anything

Coming to Elixir from Ruby, I am used to being able to interpolate literally anything into a string. In Elixir, this is not the case.

By default, it handles strings, atoms (including nil, true, false and module name aliases like String – which are all just atoms behind the scenes), integers, floats, and some lists. That's it.

There are two approaches you can take to interpolate everything else into a string. The easier approach is to use Kernel.inspect/2.

> IO.puts "A map #{inspect %{a: 1, b: 2}}"
A map %{a: 1, b: 2}

The other approach is to implement the String.Chars protocol for the thing that you are trying to print. You can read more about that in Elixir String Interpolation for Rubyists.