Elixir — A slice of Shinjuku in Erlang

Shinjuku is a dessert available at Secret Recipe, a Malaysian food chain. This is a must try if you ever visit Secret Recipe.

Erlang & Elixir are widely used functional programming language. Elixir runs on Erlang VM. Sometimes it may happen that you want to use Erlang code in Elixir and vice-versa. Here is a detailed guide how you can do that.

For simplicity let’s assume we have two project one is in Erlang and another is in Elixir. We will call a hello function of Elixir from Erlang and another hello function of Erlang from Elixir. Also assume we have two modules ‘Erlang — erlang_test_cli’ and ‘Elixir — ElixirTest’.

Setup — To get started for Erlang we have to setup few things. One is Elixir standard library and another is Elixir binary. Have a look on below codebase. We have added elixir ebin and elixir binary using code:add_path() . Then we have started compiler module and elixir module. Now you are ready to go…

load_elixir() ->
  code:add_path("/usr/local/Cellar/elixir/1.7.2/lib/elixir/ebin/"),
  code:add_path("/Users/sakib/ElixirProjects/elixir_test/_build/dev/lib/elixir_test/ebin"),
  application:start(compiler),
  application:start(elixir),
  ok.

Uses — Go through below code. In our Erlang module erlang_test_cli we are calling elixir module 'Elixir.ElixirTest':hello() . So to call elixir the format is 'Elixir.ElixirModuleName':functionName() . Lets check if it works.

-module(erlang_test_cli).
-author("sakib").

%% API
-export([hello/0, another_hello/0]).

%%% Calling Elixir from Erlang
hello() ->
  'Elixir.ElixirTest':hello().

another_hello() ->
  "Hello from Erlang".

Elixir Code,

defmodule ElixirTest do

  def hello do
    IO.puts("Welcome from Elixir.")
  end

  ### Calling Erlang from Elixir
  def anotherHello() do
    IO.puts(:erlang_test_cli.another_hello())
  end
  
end

Test —

%%% Compile
rebar3 compile
%%% Opening erlang shell with erlang_test project's binary
erl -pa _build/default/lib/erlang_test/ebin
%%% Calling load_elixir() to setup elixir dependencies
erlang_test_app:load_elixir().
%%% Calling hello from erlang_test_cli module which calls Elixir
erlang_test_cli:hello().
%%% Output
Welcome from Elixir.
ok

See we have to got result as expected. ❤

Now time to check if we can use Erlang library in Elixir.

We have a Elixir project created with Mix. Mix is a Elixir build tool.

# Calling Erlang from elixir
:erlang_test_cli.another_hello()

If you want to call Erlang code from Elixir the format is :module_name.function_name() .

Setup — This is much more straightforward than Erlang. Just add Erlang project as a dependency in mix.

# Run "mix help deps" to learn about dependencies.
defp deps do
  [
    # {:dep_from_hexpm, "~> 0.3.0"},
    # {:dep_from_git, git: "https://github.com/elixir-lang/my_dep.git", tag: "0.1.0"},
    {:erlang_test, git: "https://github.com/s4kibs4mi/erlang_test.git"}
  ]
end

See we have added our erlang_test project as a dependency.

# Get dependencies
mix deps.get
# Compile
mix compile
# Run elixir_test project's binary with elixir shell
ies -S mix
# Calling Erlang from elixir
ElixirTest.anotherHello()
# Output
Hello from Erlang
:ok

See we have got our result as expected this time as well ❤

It doesn’t matter whether you start your code with Erlang or Elixir. You can reuse it always.

Keep Coding & Go functional. ❤