(** This module provides a uniform way of reporting (located) error message. *)

(** [exit_if_error ()] forces the program to stop if an error is encountered. 
    (This is the default behavior.) *)
val exit_if_error: unit -> unit

(** [resume_if_error ()] makes the program throw the exception {!Error}
    if an error is encountered. *)
val resume_if_error: unit -> unit

exception Error of Position.t list * string

(** [print_error positions msg] formats an error message. *)
val print_error : Position.t list -> string -> string

(** [error k p msg] prints [msg] with [k] as a message prefix and stops 
    the program. *)
val error : string -> Position.t -> string -> 'a
  
(** [error2 k p1 p2 msg] prints two positions instead of one. *)
val error2 : string -> Position.t -> Position.t -> string -> 'a
  
(** [global_error k msg] prints [msg] with [k] as a message prefix and stops 
    the program. *)
val global_error : string -> string -> 'a

(** [warning k msg] prints [msg] with [k] as a message prefix, but do
    not stop the program. *)
val warning : string -> string -> unit