What is the effect on using | without a list?

Asked Jan 23 '16 at 14:29

Active Jan 23 '16 at 15:19

Viewed 57 times

I was doing this in iex:

Interactive Elixir (1.3.0-dev) - press Ctrl+C to exit (type h() ENTER for help)
iex(1)> a = [1]
[1]
iex(2)> b = [a | [2]]
[[1], 2]
iex(3)> [head | tail] = b
[[1], 2]
iex(4)> head
[1]
iex(5)> tail
[2]
iex(6)> n = [1]
[1]
iex(7)> o = [1 | 2]
[1 | 2]
iex(8)> [h | t] = o
[1 | 2]
iex(9)> h
1
iex(10)> t
2

What is/is there the/a difference between the above usages of |, and why is iex displaying them as [[1], [2]] and [1 | 2]?

edited Jan 23 '16 at 15:19

Steve Vinoski

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asked Jan 23 '16 at 14:29

Geo

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1

It's an improper list; see [this answer](http://stackoverflow.com/a/20164531/409228). – Steve Vinoski Jan 23 '16 at 14:55
1

Even if it is known as an improper list Steve - that doesn't explain why Elixir seems to prefer it in the Iex shell. – GavinBrelstaff Jan 23 '16 at 15:00
3

Elixir isn't preferring anything. `[1|2]` is an improper list, and `[1,2]` is a proper list, as is `[[1],2]`. – Steve Vinoski Jan 23 '16 at 15:05

What is the effect on using | without a list?

0 Answers0