Tonći Galić – 26 September 2016
256 words in about 2 minutes
One of the most confusing things for folks starting out with Elixir is when a list of integers gets displayed as characters in IEx console.
Let’s see an example:
1 2 | iex(1)> [7,8 ,9 ,10] '\a\b\t\n' |
The reason behind this is mentioned in the FAQ of Elixir. There are different ways to force IEx to display a list of integers:
1 . append a non-ascii printable number, like 0:
1 2 | iex(2)> [7,8 ,9 ,10] ++ [0] [7, 8, 9, 10, 0] |
2 . instruct inspect/2 not to treat input list as charlist
1 2 | iex(3)> inspect [27, 35, 51], char_lists: false [27, 35, 51] |
However, both can be annoying as you have to think ahead how your input will be shown. There’s a third, less known option:
3 . configure IEx to always use inspect/2 with the above option
1 2 3 4 | iex(4)> IEx.configure inspect: [char_lists: false] :ok iex(5)> [7,8, 9,10] [7, 8, 9, 10] |
If you’re starting out, you might want to add that to your ~/.iex.exs (which is run every time you start IEx). You can also undo that behaviour:
1 2 3 4 | iex(6)> IEx.configure inspect: [char_lists: :as_char_lists] :ok iex(7)> [7,8 ,9 ,10] '\a\b\t\n' |
BTW, Kernel.inspect/2 has more nice features, like showing number in a different representation (binary, hex or octal). You’ll find most mentioned in the docs (from console: h Kernel.inspect or online ):
1 2 3 4 5 6 | iex(8)> inspect(100, base: :binary) "0b1100100" iex(9)> inspect(100, base: :hex) "0x64" iex(10)> inspect(100, base: :octal) "0o144" |
Feel free to share any tips/tricks you know in the comments below :D