String.to_existing_atom/1 is a double-edged sword

hello@nietaki.com (nietaki) — Tue, 04 Dec 2018 13:21:00 +0000

I’d argue Elixir has relatively few gotchas. It’s a simple and consistent language and when you first learn it there’s only a few things that are genuinely counter-intuitive and catch you by surprise.

One of the examples could be the difference between binaries and charlists and why iex sometimes seems to do weird things to your lists:

iex> l = [19, 7, 16, 119, 97, 116]
[19, 7, 16, 119, 97, 116]
iex> Enum.drop(l, 1)
[7, 16, 119, 97, 116]
iex> Enum.drop(l, 2)
[16, 119, 97, 116]
iex> Enum.drop(l, 3)
'wat'

One of the other ones comes when you start working with atoms and get a little too trigger-happy with them. What you could hear from your more experienced teammates is something like this:

Gotchas on almost done

String​.to_existing_atom​/1 is a double-edged sword

String.to_existing_atom/1 is a double-edged sword