List

List is a list data type.

The list may contain elements of various types, including nested lists.

The maximim number of list items is 1000. The nesting depth is not limited. For weight restrictions, see the Data Weight article.

List Operations

Lists support concatenation, as well as adding items to the beginning and the end.

Operation	Symbol	Complexity
Concatenation	++	4
Adding the element to the end of the list (the list is on the left, the element is on the right)	:+	1
Adding the element to the beginning of the list (the element is on the left, the list is on the right)	::	2

⚠️ ++ and :+ operators are added in Standard library version 4 which becomes available after activation of feature #15 “Ride V4, VRF, Protobuf, Failed transactions” (currently on Stagenet only).

Example

nil :+ 1 :+ 2 :+ 3

Result: [1, 2, 3]

1 :: 2 :: 3 :: nil

Result: [1, 2, 3]

let intList  = [1, 2]             # List[Int]
let strList  = ["3", "4"]         # List[String]
let joined   = intList ++ strList # List[Int|String]
joined

Result: [1, 2, "3", "4"]

let appended = joined :+ true     # List[Boolean|Int|String]
appended

Result: [1, 2, "3", "4", true]

let nested    = intList :: joined  # List[Int|List[Int]|String]
nested

Result: [[1, 2], 1, 2, "3", "4"]