Data.List.Scroll

This module provides functions for relocate an item within a list.

Documentation

up :: Int -> Int -> [a] -> [a]

The up function moves an element n positions to the beginning of a list. If the index provided is out of range, the list is returned without any modification. On the other hand, extra steps will be ignored.

Some examples are given below:

>>> up 2 2 ["one", "two", "three"]
["three", "one", "two"]

>>> up 4 1 ["one", "two", "three"]
["one", "two", "three"]

>>> up 2 3 ["one", "two", "three"]
["three", "one", "two"]

down :: Int -> Int -> [a] -> [a]

The down function moves an element n positions to the end of a list. If the index provided is out of range, the list is returned without any modification. On the other hand, extra steps will be ignored.

Some examples are given below:

>>> down 0 1 ["one", "two", "three"]
["two", "one", "three"]

>>> down 4 1 ["one", "two", "three"]
["one", "two", "three"]

>>> down 0 4 ["one", "two", "three"]
["two", "three", "one"]

deleteByIndex :: Int -> [a] -> [a]

The deleteByIndex function removes an element from a list by its position within it. For example,

>>> deleteByIndex 1 ["one", "two", "three"]
["one", "three"]

If index is out of range, the list will be returned with no changes. For example:

>>> deleteByIndex 3 ["one", "two", "three"]
["one", "two", "three"]