(** Source locations. Every form carries one: error messages, the step debugger
    and nREPL's find-definition all need them, and retrofitting locations onto a
    reader is far worse than carrying them from the start. *)

type t = {
  file : string;
  line : int;  (* 1-based *)
  col  : int;  (* 1-based *)
}

let make file line col = { file; line; col }
let unknown = { file = "<unknown>"; line = 0; col = 0 }

let to_string t = Printf.sprintf "%s:%d:%d" t.file t.line t.col

(** Raised by every stage of the frontend. *)
exception Error of t * string

let fail loc fmt = Printf.ksprintf (fun msg -> raise (Error (loc, msg))) fmt