## Presence [](https://circleci.com/gh/wnuqui/presence)
Presence is very small library for Elixir projects that needs to check if a value is blank. A value is blank if it's nil, false, empty, or a whitespace string.
The complete documentation for Presence is located [here](https://hexdocs.pm/presence).
## Getting Started
Some examples can be found below, but I highly recommend you review the
API docs [here](https://hexdocs.pm/presence). There are examples for `Atom`, `BitString`, `List`, `Map` and `Tuple`.
### Adding Presence To Your Project
To use Presence with your projects, edit your `mix.exs` file and add it as a dependency:
```elixir
defp deps do
[{:presence, "~> 0.8.1"}]
end
```
### Examples
To use Presence, I recommend you add
```elixir
import Presence
```
to the top of the module where you will be working with Presence module. We `import` to easily access functions from modules implementing `Presence` protocol without using the fully-qualified name.
These functions are `is_blank/1`, `is_present`, `presence`
Few examples below:
```elixir
iex> is_blank(nil)
true
```
```elixir
iex> is_blank([])
true
```
```elixir
iex> is_blank(%{})
true
```
```elixir
iex> is_present({:ok, %{data: [1, 2, 3]}})
true
```
```elixir
iex> is_present({})
false
```
```elixir
iex> presence(" ")
nil
```
## Current Implementation
Presence is a Protocol that is currently implemented by the following:
* Atom
* List
* BitString
* Map
* Tuple
Other modules can implement the Protocol by defining these functions:
- `is_blank/1`
- `is_preent/1`
- `presence/1`
## Inspiration
Many thanks to [Rails](http://rubyonrails.org/) for the inspiration.
## License
This software is licensed under [the MIT license](LICENSE.md).
