# Digester
`Digester` provides a set of utilities for obtaining **digests** from Elixir primitives. Digests are useful to determine if a value has changed, for example, in a cache.
## Installation
The package can be installed by adding `digester` to your list of dependencies in `mix.exs`:
```elixir
def deps do
[
{:digester, "~> 0.2.0"}
]
end
```
## Usage
To obtain a digest from a value or a set of values, you'll have to first create an instance of `Digester`:
```elixir
digester = Digester.new() # Defaults to the SHA256 algorithm
# You can specify the algorithm to use
digester = Digester.new(:sha256)
```
Then, you can use `Digester.combine/2` for every value you'd like to include in the digest:
```elixir
digester = digester
|> Digester.combine("foo")
|> Digester.combine(%{bar: "baz"})
```
Remember that **the order** in which you combine values matters, so the following will produce a different digest:
```elixir
digester = digester
|> Digester.combine(%{bar: "baz"})
|> Digester.combine("foo")
```
Finally, you can obtain the digest by calling `Digester.finalize/1`:
```elixir
digest = Digester.finalize(digester)
```
`digest` will be a `String` containing the digest of the values you combined.