Red
===

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Persist relationships between objects in Redis, in a graph-like way.

**Note**: at this point, highly experimental. Not ready for production.

![](http://plusredelixir.com/wp-content/uploads/2012/02/new-power-elixir-can1.png)

### Relations

```elixir

defmodule Followers do

  def following(user) do
    user
      |> Red.rel(:in, :follow)
  end

  def followed_by(user) do
    user
      |> Red.rel(:out, :follow)
  end

  def common_following(users) do
    users
      |> Stream.map(&following &1)
      |> Red.intersect
  end

  def common_followed_by(users) do
    users
      |> Stream.map(&followed_by &1)
      |> Red.intersect
  end

end

# get most recent 20 followers of user 42
{:user, 42}
  |> Followers.following
  |> Red.limit(20)
  |> Red.fetch!

=> [21, 666, 57]

# get most recent 5 common followers of users 42 and 12
[{:user, 42}, {:user, 12}]
  |> Followers.common_following
  |> Red.limit(5)
  |> Red.fetch!
=> [21]

# users followed by 21
i_follow = Followers.followed_by("user#21")

# users followed by 42,
# showing users followed by 21 first
{:user, 42}
  |> Followers.followed_by
  |> Red.sort_by(i_follow)
  |> Red.fetch!


# makes user 21 follow user 42
{:user, 42}
  |> Followers.following
  |> Red.add({:user, 21})
```