# Chain
A library that mimics the JavaScript Promise API, but only as a synchronous way to organise code.
## Installation
Chain is [available in Hex](https://hex.pm/chain), the package can be installed
by adding `chain` to your list of dependencies in `mix.exs`:
```elixir
def deps do
[
{:chain, "~> 0.2"}
]
end
```
Documentation can be generated with [ExDoc](https://github.com/elixir-lang/ex_doc)
and published on [HexDocs](https://hexdocs.pm). Once published, the docs can
be found at [https://hexdocs.pm/chain](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)
```elixir
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](/LICENSE.md).