Allow operators to be captured, example: &+/2
Move from  // to \\
Deprecate usage of @behavior in favor of @behaviour
Address undefined macro if on bootstraping
Improve error messages for bad arity errors
Deprecate =~

Use String.contains?/2 when the right side is a string or
String.match?/2 when the right side is a regex.

The goal of this deprecation is to make space for the upcoming
`~` and `~=` operators.
Generalize unary operators followed by int have higher precedence
Fix list with keywords expansion

The list `[1, 2, three: :four]` now correctly expands
to `[1, 2, {:three, :four}]`.