Moves part of array within.
Alternatives: moveWithin, moveWithin$.
Similar: copy, copyWithin, moveWithin.
This is part of package extra-array.
array.moveWithin$(x, [j], [i], [I]);
// x: an array (updated)
// j: write index (0)
// i: read start index (0)
// I: read end index (X)
// → x
const array = require("extra-array");
var x = [1, 2, 3, 4, 5, 6];
array.moveWithin$(x, 0, 1, 3);
// [ 2, 3, 1, 4, 5, 6 ] (2,3 to left)
x;
// [ 2, 3, 1, 4, 5, 6 ]
var x = [1, 2, 3, 4, 5, 6];
array.moveWithin$(x, 6, 3, 5);
// [ 1, 2, 3, 6, 4, 5 ] (4,5 to right)