# OK Elixir

**Effecient error handling in elixir pipelines. See [Handling Errors in Elixir](http://insights.workshop14.io/2015/10/18/handling-errors-in-elixir-no-one-say-monad.html) for a more detailed explination**

[Documentation for OK is available on hexdoc](https://hexdocs.pm/ok)

## Installation

[Available in Hex](https://hex.pm/docs/publish), the package can be installed as:

  1. Add ok to your list of dependencies in `mix.exs`:

        def deps do
          [{:ok, "~> 0.0.1"}]
        end

## Usage

The OK module works with the native error handling in Erlang/Elixir, that is a result tuple.
A result tuple is a two-tuple tagged either as a success(`:ok`) or a failure(`:error`).

```elixir
{:ok, value} | {:error, reason}
```

### '~>>' Macro

This macro allows pipelining result tuples through a pipeline of functions.

```elixir
import OK, only: :macros

def get_employee_data(file, name) do
  {:ok, file}
  ~>> File.read
  ~>> Poison.decode
  ~>> Dict.fetch(name)
end

def handle_user_data({:ok, data}), do: IO.puts("Contact at #{data["email"]}")
def handle_user_data({:error, :enoent}), do: IO.puts("File not found")
def handle_user_data({:error, {:invalid, _}}), do: IO.puts("Invalid JSON")
def handle_user_data({:error, :key_not_found}), do: IO.puts("Could not find employee")

get_employee_data("my_company/employees.json")
|> handle_user_data
```