aoc2020/bracket.ml

let bracket ~make:(lazy x) ~act ~free =
  match act x with
  | result      -> free x; result
  | exception e -> free x; raise e

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