List module

The List module contains functions to deal with lists. Lists are actually Linked List.

at/2

List.at(["a", "b", "c"], 0)     # "a"
List.at(["a", "b", "c"], 1)     # "b"
List.at(["a", "b", "c"], 2)     # "c"
List.at([], 0)                  # nil

Parameters:

• list the list
• index the index (zero-based)

Returns the element at index in list.

size/1

List.size([])           # 0
List.size([1,2,3,4])    # 4

Parameters:

• list the list

Returns the number of keys in list.

in?/2

List.in?(["bob", "alice"], "alice") # true
List.in?(["bob", "alice"], "fred")  # false

Parameters:

• list the haystack
• element the needle

Returns whether the needle is in the haystack.

empty?/1

List.empty?([])         # true
List.empty?(["apple"])  # false

Parameters:

• list the list

Returns whether the list is empty or not.

concat/2

List.concat([], [])         # []
List.concat([1,2], [3,4])   # [1,2,3,4]

Parameters:

• list1 a list
• list2 another list

Returns a new list where list2 is concatenated to list1.

append/2

List.append([], 1)    # [1]
List.append([1], 2)   # [1,2]

Parameters:

• list the list
• element the element

Returns a new list where element is appended to the end of list.

tip

If order doesn't matter, we suggest to use prepend/2 instead (Complexity: O(1) instead of O(n)).

prepend/2

List.prepend([], 1)    # [1]
List.prepend([1], 0)   # [0,1]

Parameters:

• list the list
• element the element

Returns a new list where element is appended to the start of list.

join/2

List.join([], ", ")    # ""
List.join(["Mike", "Robert", "Joe"], ", ")   # "Mike, Robert, Joe"

Parameters:

• list the list of strings
• separator the separator

Returns a string where all list's elements have been joined with separator separator.