[Feature] Array Destructuring

[UrbanCoffee]

Array destructuring syntax provides a quick way to assign elements of an array to multiple variables in a single line.

let array = [1,2,3,4];
let [ a, b, ...c ] = array;
echo a // "1"
echo b // "2"
echo c // "3 4"

let d = 0
let e = 0
[ d, e ] = c
echo d // 3
echo e // 4

Amber could support:

• Individual assignment. The number of variables to unpack and the length of the array need not be the same.

  let [ a, b ] = array;
  echo a // "1"
  echo b // "2"

  However, there is the question of what to do when there are more variables than elements in the array.

  let array = [1];
  let [ a, b ] = array;
  echo b // ??

• Ignore array elements. Individual elements in the array can be skipped or ignored when assigning to variables.

  let [ , a ] = array; // or [ _, a ]
  echo a // "2"

• Trailing spread operator. Assign the remaining subarray into a variable.

  let [ a, ...b ] = array;
  echo a // "1"
  echo b // "2 3 4"

  This feature should perhaps be deferred to a later version as the presence of the spread operator here can lead people to believe that the spread operator can be used elsewhere like in array construction.

  let arr_A = [1,2]
  let arr_B = [...arr_A, 3]
  echo arr_B // "1 2 3"

This Gist by JTBrinkmann demonstrates how a destructuring function could be implemented. However, each implementation involves globally declaring variables which would be troublesome when used inside a function.

[b1ek]

this kind of split should be done compile time like this without the need to create a function and assign variables globally

let [ a, b ] = array;

let a = array[0];
let b = array[1];