Hi folks, I’ve been running into some very strange behavior that has me knocking my head against the wall. If I run the following code: ["42", "12", "15"] |> Enum.map(&(String.to_integer(&1))) I get what you’d expect: the list [42, 12, 15] But if I run this code: ["41", "92", "73", "84", "69"] …

congrats on reaching this milestone - and completing a major step/rite of passage on your elixir journey - it’s a charlist Binaries, strings, and charlists — Elixir v1.21.0-dev we have all been there - and gone through the same wtf etc.

Try this to force lists of integers to display as lists of integers (reference: Inspect.Opts — Elixir v1.12.3 ): ["41", "92", "73", "84", "69"] |> Enum.map(&(String.to_integer(&1))) |> IO.inspect(charlists: :as_lists)

[image] mindok: |> IO.inspect(charlists: :as_lists) That this is not the default is a little crazy to me.

It is a tribute to the Erlang community :slight_smile:

Yeah, you are basically seeing the runtime trying to be a bit too helpful – if a list of integers looks like a list of printable characters, then the REPL will instead show them as a printable string. The data is still there and is still the same. If you want to get rid of that behavior in your pro…

The problem I run into is that it does not apply to any IO.inspect calls within the code. You have to remember to do IO.inspect(number_list_that_isnt_supposed_to_be_chars, charlists: :as_lists) every time you might be faced with this weirdness.

I think it’s time to make charlists: :as_lists to be a default option, and deprecate the charlists: :infer option.

I think that would just surface how often we actually run into charlists when interacting with erlang libraries. E.g. hardly any elixir app doesn‘t use gen_tcp somewhere. From my personal experience I‘ve been hitting the case of needing to see the underlying list of integers mostly in tests or puzz…

Hehe I was right here [image] Convert 'charlists' into ~c"charlists" Official Proposals I think it is equally confusing. We’ll simply achieve changing of wording a bit in topics from newcomers, so instead of why [97, 98, 99] prints ‘abc’? we’ll have why …

At least now there is the chance that someone can look up the documentation for the ~c sigil. Just because it didn’t happen in this case it does not mean it’s not an improvement.

Why does String.to_integer/1 give strange results with with some values?

Questions & Help Questions

stevensonmt December 8, 2023, 1:06am 4

That this is not the default is a little crazy to me.