* http://cs.unibo.it/helm/.
*)
-type failure_msg
-
-exception UnificationFailure of failure_msg;;
-exception Uncertain of string;;
-exception AssertFailure of failure_msg;;
-
-val failure_msg_of_string: string -> failure_msg
-val explain_error: failure_msg -> string
+exception UnificationFailure of string Lazy.t;;
+exception Uncertain of string Lazy.t;;
+exception AssertFailure of string Lazy.t;;
(* fo_unif metasenv context t1 t2 *)
(* unifies [t1] and [t2] in a context [context]. *)