Exploring Graphs with Elixir

Reaching Back to the ARPANET

We’re going to revisit another graph we’ve seen before, the ARPANET, and look at some additional DQL features: inverses, paths, and recursion. So, let’s set up a Dgraph schema for this.

We start by clearing out the graph service of schemas and data:

iex> graph_delete
""

We can now read our Dgraph schema from the graph store:

iex> IO.puts (arpa70_schema = read_graph "schemas/arpa70.schema").data
name: string @index(term) .
type: string @index(term) .

H_LINK: [uid] @reverse .
N_LINK: [uid] .

type Host {
  name
  type
  <~H_LINK>
}

type Node {
  name
  type
  N_LINK
}

:ok

No surprise here, apart from the @reverse directive set on the H_LINK predicate. Also, note the ...