Is it possible to implement a method

insert

(or

prepend

) to the

StringBuilder

class? There already is

append

it will not be very efficient, builder leaves free space after last inserted character. Better use MutableList to store all prefixes and build final sting passing this list in backward direction.

That sounds quite cumbersome. Idk if inefficient performance is a good argument to leave out functional features, but at least I got an answer why it is being left out. JVM and Native do have an implementation though, so I would think it is possible....