Example (lines 9 & 10) are from http://learnyousomeerlang.com/starting-out-for-real#lists
Both ++ and -- are right-associative. This means the elements of many -- or ++ operations will be done from right to left, as in the following examples:
9> [1,2,3] -- [1,2] -- [3].
[3]
10> [1,2,3] -- [1,2] -- [2].
[2,3]