let bracket ~make:(lazy x) ~act ~free =
  Fun.protect (fun () -> act x) ~finally:(fun () -> free x)

let infile ~act name =
  bracket ~make:(lazy (open_in name)) ~act ~free:close_in_noerr

let infile_lines ~line:f ~of_seq name =
  let get_line file =
    try Some (f (input_line file), file)
    with End_of_file -> None in
  let act file = of_seq (Seq.unfold get_line file) in
  infile name ~act

let infile_iter_lines ~line ~iter = infile_lines ~of_seq:(Seq.iter iter) ~line

let infile_chunks ~chunk ~of_seq input =
  let of_seq seq = Seq.line_chunks seq |> Seq.map chunk |> of_seq in
  infile_lines input ~line:Fun.id ~of_seq