Simple, messy run-length encoder

gistfile1.txt

let inline f tolerance data =
  let two = LanguagePrimitives.GenericOne + LanguagePrimitives.GenericOne
  data |> List.mapi (fun i c -> i, c)
  |>function
    | (_,c)::tl ->
      tl
      |> List.fold (fun (rest, (min, max), x) (i, c) ->
        if abs (x-c) <= tolerance
        then rest, (min, max+1), (x+c)/two
        else ((min,max),x) :: rest, (i, i), c)
        ([],(0,0),c)
      |> function | d, (min, max), x -> ((min, max), x) :: d
    | [] -> []
  |> List.rev

f 0.5 <| List.map (fun n -> n / 3.) [0. .. 30.]
f 0.5 [1.6; 1.24; 1.99; 2.32; 2.48; 2.53; 2.38; 2.12; 4.97; 5.18; 9.4; 3.14; 3.44]  // [((0, 1), 1.42); ((2, 7), 2.2609375); ((8, 9), 5.075); ((10, 10), 9.4); ((11, 12), 3.29)]
f 0.5 List.empty<float>                                                             // []