Handoff Branching DAG Example

This Livebook demonstrates how to build and execute a branching (tree-like) DAG using the Handoff library in Elixir.

Setup

First, install the required dependencies:

Mix.install([
  {:handoff, "~> 0.1"}
])

# Define transformation functions in a dedicated module

defmodule Transformations do
  def identity(x), do: x
  def double(x), do: x * 2
  def triple(x), do: x * 3
  def sum_two_lists(d, t), do: Enum.sum(d) + Enum.sum(t)
end

Define the DAG

alias Handoff.Function

dag = Handoff.new()

# Source node
data = [1, 2, 3, 4, 5]
source_fn = %Function{
  id: :data_source,
  args: [],
  code: &Transformations.identity/1,
  extra_args: [data]
}

# Two parallel transformations
transform_double = %Function{
  id: :double,
  args: [:data_source],
  code: &Enum.map/2,
  extra_args: [&Transformations.double/1]
}

transform_triple = %Function{
  id: :triple,
  args: [:data_source],
  code: &Enum.map/2,
  extra_args: [&Transformations.triple/1]
}

# Aggregation node
aggregate_fn = %Function{
  id: :sum,
  args: [:double, :triple],
  code: &Transformations.sum_two_lists/2
}

dag =
  dag
  |> Handoff.DAG.add_function(source_fn)
  |> Handoff.DAG.add_function(transform_double)
  |> Handoff.DAG.add_function(transform_triple)
  |> Handoff.DAG.add_function(aggregate_fn)

:ok = Handoff.DAG.validate(dag)
dag

Execute the DAG

{:ok, results} = Handoff.execute(dag)

IO.inspect(results, label: "All results")
IO.puts("The sum is: #{results[:sum]}")