# Readable

Elixir language have standard `String.Chars` protocol which describes `T -> String` relation (like Haskell [Show](https://www.haskell.org/haddock/libraries/GHC.Show.html) type class). But Elixir don't have any standard protocol for `String -> T` relation (some equivalent of Haskell [Read](https://www.haskell.org/haddock/libraries/GHC.Read.html) type class). But I think such protocol completely make sense.

This protocol describes read relation between 2 types. Instance of type `B` can be read from instance of type `A`. Usually type `A = String`, but this implementation don't have this constraint.

<img src="priv/img/logo.png" width="300"/>

## Example

```elixir
import Read

defreadable Integer, from: x :: BitString do
  String.to_integer(x)
end

defreadable URI, from: x :: BitString do
  URI.parse(x)
end
```

and then we can use implementation of `Read` type class

```elixir
iex> Read.read("123", Integer)
123

iex> Read.read("https://hello.world", URI)
%URI{
  authority: "hello.world",
  fragment: nil,
  host: "hello.world",
  path: nil,
  port: 443,
  query: nil,
  scheme: "https",
  userinfo: nil
}

iex> Read.read("https://hello.world", TypeNotExist)
** (ArgumentError) argument error
    :erlang.binary_to_existing_atom("Elixir.Readable.From.BitString.To.TypeNotExist", :utf8)
    (elixir) src/elixir_aliases.erl:119: :elixir_aliases.safe_concat/1
    (readable) lib/read.ex:84: Read.read/2
```

## Installation

The package can be installed by adding `readable` to your list of dependencies in `mix.exs`:

```elixir
def deps do
  [
    {:readable, "~> 0.1.0"}
  ]
end
```