🤔 How to inject a list into a quoted expression

Notes

A couple of tips ago, we saw how to use Elixir’s quote/1 and unquote/1 to inject values into our quoted expressions.

But how can we inject a list into a quoted expression that has a list while flattening it’s values?

Turns out quote/1 doesn’t quite do the trick:

iex> list = [1, 2, 3]
iex> a = quote do: [unquote(list), 4, 5, 6]
#=> [[1, 2, 3], 4, 5, 6]

That’s disappointing. Isn’t it?

Most of the times we want it to return [1, 2, 3, 4, 5, 6].

Thankfully, Elixir has a helper to help us with exactly that problem! It’s called unquote_splicing/1:

iex> list = [1, 2, 3]
iex> a = quote do: [unquote_splicing(list), 4, 5, 6]
#=> [1, 2, 3, 4, 5, 6]

That’s more like it!