FoldLeft

Description

The listutils:fold_left function folds the list into one value from the smallest index to the largest index, using a fold function.

Usage

Input is given using the listutils:in storage:

Field	Meaning
List	The list to fold.

Optionally, a fold function can be specified in the $listutils.function listutils.in score. This argument defaults to function 0, which sums all elements in the list.

After defining the input, run the function listutils:fold_left.

Fold functions

Various fold functions can be used to fold a list. For more about fold functions, see the Fold functions page.

Errors

Errors that display when executing the listutils:fold_left function as a player in debug mode.

Error	Message
TBD	TBD

Return values

Success

The success of the operation is stored in the $listutils.success listutils.out score. This score is 1 on success and 0 otherwise. By default, the success is always 1 when not running in debug mode. This can be changed in the fold function.

Result

The result of the operation is stored inside the Data field in the listutils:out storage, or in the $listutils.result listutils.out score. Which one is used depends on the fold function.

Example

Take the example list ExampleList: ["foo", "Hello World!", "foo", "bar"] in the listutils:examples storage. We want to take the average length of a string in the list:

# Get list length.
execute store result score $length var run data get storage listutils:examples ExampleList
# Add List to the input.
data modify storage listutils:in List set from storage listutils:examples ExampleList
# Add the fold function to the input.
scoreboard players set $listutils.function listutils.in 0
# Call the function.
function listutils:fold_left
# Divide the result by the length of the list.
scoreboard players operation $listutils.result listutils.out /= $length var

This would return 30 in the $listutils.result listutils.out score as the result of the operation. The final average is 7.