Contiguous List.partition_by OCaml

list_partition_by_contiguous.ml

(* Split a list when the predicate changes when comparing two neighbours *)

let partition_by (predicate : 'a -> 'a -> bool) (xs : 'a list) : ('a list) list =
  let rec go (cur_x, cur_xs, acc : 'a * ('a list) * (('a list) list)) (xs : 'a list) : ('a list) list =
    match xs with
    | [] -> (List.rev ((List.rev cur_xs) :: acc))
    | x :: xs ->
      if predicate x cur_x
      then go (x, x :: cur_xs, acc) xs
      else go (x, [x], (List.rev cur_xs) :: acc) xs
  in
  match xs with
  | x :: xs -> go (x, [x], []) xs
  | [] -> []