More Complex List Patterns

The join operator |

Not every list problem can be easily solved by processing one element at a time. Fortunately, the join operator, |, supports multiple values to its left. Thus, we can write the following:

iex> [ 1, 2, 3 | [ 4, 5, 6 ]] 
[1, 2, 3, 4, 5, 6]

The same thing works in patterns, so we can match multiple individual elements as the head. For example, the following program swaps pairs of values in a list.

Run the Swapper.swap([1,2]) command in the terminal below.