Babel

Data transformations made easy.

Table of Contents

• Table of Contents
• Installation
• Usage
  • Error Reporting
• Contributing

Installation

Simply add babel to your list of dependencies in your mix.exs:

def deps do
  [
    {:babel, "~> 1.0"}
  ]
end

Differences between the versions are explained in the Changelog.

Documentation gets generated with ExDoc and can be viewed at HexDocs.

Usage

Babel was born out of a desire to simplify non-trivial data transformation pipelines. To focus on the "happy path" instead of having to write a bunch of boilerplate error handling code.

But don't listen to me, take a look for yourself:

pipeline =
  Babel.begin()
  |> Babel.fetch(["some", "nested", "path"])
  |> Babel.map(Babel.into(%{atom_key: Babel.fetch("string-key")}))

data = %{
  "some" => %{
    "nested" => %{
      "path" => [
        %{"string-key" => :value2},
        %{"string-key" => :value2},
        %{"string-key" => :value2}
      ]
    }
  }
}

Babel.apply(pipeline, data)
=> {:ok, [
   %{atom_key: :value1},
   %{atom_key: :value2},
   %{atom_key: :value3}
]}

Error Reporting

Since you'll most likely build non-trivial transformation pipelines with Babel - which can fail at any given step - Babel ships with elaborate error reporting:

pipeline =
  Babel.begin()
  |> Babel.fetch(["some", "nested", "path"])
  |> Babel.map(Babel.into(%{atom_key: Babel.fetch("string-key")}))

data = %{
  "some" => %{
    "nested" => %{
      "path" => [
        %{"unexpected-key" => :value1},
        %{"unexpected-key" => :value2},
        %{"unexpected-key" => :value3}
      ]
    }
  }
}

Babel.apply(pipeline, data)
=> {
  :error,
  %Babel.Error{
    reason: [
      not_found: "string-key",
      not_found: "string-key",
      not_found: "string-key"
    ],
    trace: Babel.Trace<ERROR>{
      data =
        %{
          "some" => %{
            "nested" => %{
              "path" => [
                %{"unexpected-key" => :value1},
                %{"unexpected-key" => :value2},
                %{"unexpected-key" => :value3}
              ]
            }
          }
        }

      Babel.Pipeline<>
      |
      | Babel.fetch(["some", "nested", "path"])
      | |=< %{"some" => %{"nested" => %{"path" => [%{"unexpected-key" => :value1}, %{...}, ...]}}}
      | |=> [%{"unexpected-key" => :value1}, %{"unexpected-key" => :value2}, %{"unexpected-key" => :value3}]
      |
      | Babel.map(Babel.into(%{atom_key: Babel.fetch("string-key")}))
      | |=< [%{"unexpected-key" => :value1}, %{"unexpected-key" => :value2}, %{"unexpected-key" => :value3}]
      | |
      | | Babel.into(%{atom_key: Babel.fetch("string-key")})
      | | |=< %{"unexpected-key" => :value1}
      | | |
      | | | Babel.fetch("string-key")
      | | | |=< %{"unexpected-key" => :value1}
      | | | |=> {:error, {:not_found, "string-key"}}
      | | |
      | | |=> {:error, [not_found: "string-key"]}
      | |
      | | Babel.into(%{atom_key: Babel.fetch("string-key")})
      | | |=< %{"unexpected-key" => :value2}
      | | |
      | | | Babel.fetch("string-key")
      | | | |=< %{"unexpected-key" => :value2}
      | | | |=> {:error, {:not_found, "string-key"}}
      | | |
      | | |=> {:error, [not_found: "string-key"]}
      | |
      | | Babel.into(%{atom_key: Babel.fetch("string-key")})
      | | |=< %{"unexpected-key" => :value3}
      | | |
      | | | Babel.fetch("string-key")
      | | | |=< %{"unexpected-key" => :value3}
      | | | |=> {:error, {:not_found, "string-key"}}
      | | |
      | | |=> {:error, [not_found: "string-key"]}
      | |
      | |=> {:error, [not_found: "string-key", not_found: "string-key", not_found: "string-key"]}
      |
      |=> {:error, [not_found: "string-key", not_found: "string-key", not_found: "string-key"]}
    }
  }
}

Babel achieves this through a custom implementation of the Inspect protocol for Babel.Trace. As such you'll have access to them everywhere; in the Babel.Error message, in iex, and whenever you inspect a Babel.Error or Babel.Trace.

Contributing

Contributions are always welcome but please read our contribution guidelines before doing so.