Elixir uses two files,
.ex for compiled code and
.exs for scripts. They must both be UTF-8 encoded. We will go over
.ex some more when we introduce mix in the next chapter. But for now, let's discuss
.exs a little more.
We can write all the Elixir code we have shown so far into a script (we won't though, there is just a small subset) and then we can use the interactive interpreter to load up our script and run it.
For example, we can put the
MyMap code from earlier into a script:
defmodule MyMap do def map(, _) do  end def map([h|t], f) do [f.(h) | map(t, f)] end end square = fn x -> x * x end MyMap.map([1, 2, 3, 4, 5], square)
Go ahead and save it as
mymap.exs. Launch a terminal and use the
cd command to navigate to the directory ...