Breaks iterable considering indices as separator.
This is part of package extra-array.
array.splitAt(x, is);
// x: an array
// is: indices (sorted)
const array = require("extra-array");
var x = [1, 2, 2, 3, 5, 4, 4, 7];
array.splitAt(x, [1, 2, 5, 6]);
// [ [ 1 ], [ 3, 5 ], [ 7 ] ]
var x = [2, 4, 5, 6, 8];
array.splitAt(x, [0, 1, 3, 4]);
// [ [ 5 ] ]