Chain

A library that mimics the JavaScript Promise API, but only as a synchronous way to organise code.

Installation

Chain is available in Hex, the package can be installed by adding chain to your list of dependencies in mix.exs:

def deps do
  [
    {:chain, "~> 0.2"}
  ]
end

Documentation can be generated with ExDoc and published on HexDocs. Once published, the docs can be found at https://hexdocs.pm/chain.

Usage

A Chain is a list of steps to run sequentially. Each next step gets the previous result as parameter and if returns {:ok, value} or value then value goes to the next next step in line. If it returns a {:error, reason} tuple, then reason goes to the next recover step in line.

There are three types of steps:

• next: step that gets the previous result as parameter.
• recover: step that gets the previous error as parameter.
• capture: step that gets any raised error in the previous steps. (if arity 1, gets the error, if arity 2, gets the error and the stacktrace)

chain_result =
  initial_value
  |> Chain.new()
  |> Chain.next(&do_some_work/1)
  |> Chain.next(&do_some_more_work/1)
  |> Chain.recover(&recover_some_error/1)
  |> Chain.next(&do_some_other_work/1)
  |> Chain.capture(&manage_unexpected_runtime_errors/2)
  |> Chain.run()

License

Licensed under the MIT License. See License file.