# Mex

An Elixir Shell [helper for previewing macroexpansion](blog.maketogether.com/elixir/).

![Screenshot](screen.png)


## Installation

Install by adding a **dev** dependency on `mex`:

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

        def deps do
          [{:mex, "~> 0.0.1", only: :dev}]
        end

  2. Ensure mex is started before your application:

        def application do
          [applications: [:mex]]
        end

Then import and it in your project's `.iex.exs`:

```elixir
import Mex
Mex.set_width 160   # (optional) default width is 80 chars
```


## Usage

```elixir
mex do
  expr  # <-- expression you'd like expanded.
end
```

By default, `mex` will display 4 columns: `no_expansion`,
`Macro.expand_once`, `Macro.expand`, and `Mex.expand_all`.

You can specify how many columns you want (1-4) by passing
an argument to `mex` before the block:

```elixir
iex(0)> import Mex
iex(2)> mex 3 do
          expression_to_macro_expand
        end
 
<will display 3 columns>
```