Programming Elixir 1.2

Other Ways to Run Code Fragments

We can use the function Code.eval_quoted to evaluate code fragments, such as those returned by quote.

iex> fragment = quote do: IO.puts("hello")
{{:.,[],[{:__aliases__,[alias: false],[:IO]},:puts]},[],["hello"]}
iex> Code.eval_quoted fragment
hello
{:ok,[]}

By default, the quoted fragment is hygienic, and so does not have access to variables outside its scope. Using var!(:name), we can disable this feature and allow a quoted block to access variables in the containing scope. In this case, we pass the binding to eval_quoted as a keyword list.

iex> fragment = quote do: IO.puts(var!(a))
{{:., [], [{:__aliases__, [alias: false], [:IO]}, :puts]}, [],
 [{:var!, [context: Elixir, ...