Alter alter

Modifies an element at a specific index using a function.

;; Basic syntax: (alter obj func index value)
;; Applies (func element value) at the specified index

;; Set element at index
↪ (set arr [10 20 30])
↪ (alter arr set 0 99)
[99 20 30]

;; Add to element at index
↪ (set arr [10 20 30])
↪ (alter arr + 1 100)
[10 120 30]

;; Multiply element at index
↪ (set arr [10 20 30])
↪ (alter arr * 2 5)
[10 20 150]

Returns New Value

alter returns a modified copy - it does NOT modify the original. To persist changes, reassign:

(set arr (alter arr set 0 99))

Syntax

(alter object function index value)

- object: Array, list, or table to modify - function: Binary function (+, *, set, etc.) - index: Index of element to modify - value: Value to apply with function

Common Functions

• set - Replace element: (alter arr set 0 99)
• + - Add to element: (alter arr + 0 10)
• * - Multiply element: (alter arr * 0 2)
• concat - Append to element (for lists)