ExUp

ExUp allows your project to use features of new Elixir versions, even when the project can't be updated to that version (yet!). This is a form of upward compatibility.

For example, your project is using Elixir < "1.13.0" and needs to filter the pairs on a map. After a quick search you find out Map.filter/2, you use it to discover that it isn't supported in this elixir version:

** (UndefinedFunctionError) function Map.filter/2 is undefined or private

Instead of implementing your own version and remembering to go back and change it after you update to Elixir >= "1.13.0" you can use ExUp's version:

ExUp.Map.filter(map, fun)

When you update, compilation will warn that the built-in functionality can be used already and the project can drop the usage of ExUp on this case.

**warning**: ExUp.Map.filter/2 is deprecated. Use Map.filter/2 directly, as we're already on 1.13.0

Installation

Add it to your dependencies:

# mix.exs
def deps do
  [
    {:ex_up, "~> 0.1.0"},
  ]
end

Documentation

Check the documentation to known what is already upwards compatible.

As the documentation is generated in newer Elixir versions all functionality will be marked as deprecated.

Caveats

• Although the implementations on ExUp will give the same results as the original version, they are not intended to be an exact copy of Elixir's code. So runtime differences may be present like performance issues.
• Some functionality are easier to replicate than other. ExUp may not be a good fit for the harder ones. Lets use this energy to really update Elixir on the projects.

Contributing

Contributions are welcome.

Running the Elixir tests:

mix deps.get
mix test

The macro ExUp.defup/5 can be used to generate code and documentation to handle Elixir versions.

defmodule ExUp.Map do
  @moduledoc since: "0.1.0"
  import ExUp
  @doc since: "0.1.0"
  defup "1.13.0", Map, :filter, [map, fun] do
    for pair <- map, fun.(pair), into: %{}, do: pair
  end
end

In current Elixir versions we should test that the "upwarded" versions behaves like the original one.

defmodule ExUp.MapTest do
  use ExUnit.Case, async: true
  describe "filter/2" do
    if Version.match?(System.version(), ">= 1.13.0") do
      test "works as Map.filter/2" do
        # ...
        assert ExUp.Map.filter(map, fun) == Map.filter(map, fun)
      end
    end
  end
end