Is there a function to insert an element at i-th position in a list?

[rupert]

@AvailableUsername

You can’t do this with better than linear time with an array.

You can, because Array.slice and Array.append are log time not linear. Of course, you will only see a difference for large enough arrays.

Check out this example of a gap buffer capable of working smoothly with 1M lines of text, implemented using arrays and making use of Array.slice and Array.append to quickly insert or refocus the ‘gap’:

https://kind-colden-ebafc2.netlify.app/

Efficient Text Editing Buffer

If a simple Array is used to hold lines of text, whenever a line is edited, the array will need to be sliced, lines modified, then put back together again. It works fine up to a limit at which point the editor becomes noticeably unresponsive. I scratched my head over this one for a while, thinking about various tree structures, or skip lists, and so on. Then the answer came to me - make a data structure like a zip list, but use arrays instead of lists. There are lots of packages implementing zi…