Anonymous functions

fizz_buzz.exs

fizz_buzz = fn
  (0,0,_) -> "FizzBuzz"
  (0,_,_) -> "Fizz"
  (_,0,_) -> "Buzz"
  (_,_,a) -> a
end
IO.puts fizz_buzz.(0,0,"foo")
IO.puts fizz_buzz.(0,"foo","bar")
IO.puts fizz_buzz.("foo",0,"bar")
IO.puts fizz_buzz.("foo","bar","Atlas")

handle_open.exs

handle_open = fn
  {:ok, file} -> "First line: #{IO.read(file, :line)}"
  {_, error} -> "Error: #{:file.format_error(error)}"
end
IO.puts handle_open.(File.open("existent")) # call with a file that exists
IO.puts handle_open.(File.open("nonexistent")) # and then with one that doesn't

prefix.exs

prefix = fn
  prefix_string -> fn
    name -> "#{prefix_string} #{name}"
  end
end
mrs = prefix.("Mrs")
IO.puts mrs.("Smith")
IO.puts prefix.("Elixir").("Rocks")