Pack Consecutive Duplicates - difference in proposed solution on the Exercises page

Learning
2

Your pack_aux is not tail recursive (acc :: pack_aux [b] tl is not a tail call).
In exchange you get to avoid having the List.rev in the other solution.
It’s a similar difference as the usual

let rec non_tailrec_map f = function
| [] -> []
| x :: tl ->
  let fx = f x in
  fx :: non_tailrec_map f tl

(* vs *)

let tailrec_map f l =
  let rec aux acc = function
    | [] -> acc
    | x :: tl -> aux (f x :: acc) tl
  in
  List.rev (aux [] l)
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