adamc@58: signature S = sig
adamc@58:         type t
adamc@58:         val x : t
adamc@58: end
adamc@58: 
adamc@58: signature S' = sig
adamc@58:         include S
adamc@58:         val y : t
adamc@58: end
adamc@58: 
adamc@58: signature S'' = sig
adamc@58:         type u
adamc@58:         include S' where type t = int
adamc@58:         type v
adamc@58: end