1.1 --- a/src/Tools/subtyping.ML	Tue Nov 26 09:49:52 2013 +0100
     1.2 +++ b/src/Tools/subtyping.ML	Tue Nov 26 10:17:14 2013 +0100
     1.3 @@ -129,7 +129,8 @@
     1.4  
     1.5  infixr ++> +@> (* lazy error msg composition *)
     1.6  
     1.7 -fun err ++> prt = err #> apsnd (cons prt);
     1.8 +fun (err : unit -> string * Pretty.T list) ++> (prt : Pretty.T) =
     1.9 +  err #> apsnd (cons prt);
    1.10  val op +@> = Library.foldl op ++>;
    1.11  
    1.12  fun eval_err err = err ()