Need some help on Elixir Lists

Questions / Help
1

iex
Erlang/OTP 18 [erts-7.3] [source] [64-bit] [smp:8:8] [async-threads:10] [hipe] [kernel-poll:false] [dtrace]

Interactive Elixir (1.2.3) - press Ctrl+C to exit (type h() ENTER for help)

List substraction

iex(10)> [12,2]–[2,3,4,5,6]
‘\f’

I was expecting answer 12, how is ‘\f’ is displayed? Also I was expecting a list but got string.

When I have the list with [1,2] and try to perform below subtraction I get expected answer [1]
iex(11)> [1,2]–[2,3,4,5,6]
[1]

Same concern I have here:
iex(12)> [13,2]–[2,3,4,5,6]
‘\r’
iex(13)> [10,2]–[2,3,4,5,6]
‘\n’

2

This should help: http://stackoverflow.com/questions/30037914/elixir-lists-interpreted-as-char-lists
And this: http://elixir-lang.org/getting-started/binaries-strings-and-char-lists.html

1 Like
3

Those links should help you out.
One important point is that ‘\f’ is not a string. It’s a charlist (single quotes for charlists and double quotes for strings), and the behavior of charlists and strings are totally different.

4

This comes up often and it’s just one of those quirks that you have to get used to. I find it helpful when in an iex session to type

iex> ?\f
12

As above, single quotes = list of characters. Dave Thomas’ book primed me wel for this idiosyncrasy.

M

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5

The i command in iex was written to help with this exact problem.

iex(1)> [12,2]–[2,3,4,5,6]
‘\f’
iex(2)> i v(1)
Term
‘\f’
Data type
List
Description
This is a list of integers that is printed as a sequence of characters
delimited by single quotes because all the integers in it represent valid
ASCII characters. Conventionally, such lists of integers are referred to as
“charlists” (more precisely, a charlist is a list of Unicode codepoints,
and ASCII is a subset of Unicode).
Raw representation
[12]
Reference modules
List

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