There is provided with a device that includes a first inputter inputting design description which includes functions; a second inputter inputting type specifying description corresponding to the functions, each of which specifies a type for a return value of each corresponding function, and the description of at least one function of the functions specifies a type for a return value of a first function which is an other function of functions; a determiner determining a type of the return value of the first function to a comprehensive type to comprehend the types specified by the type specifying description corresponding to the first function and the at least one function and a type of the return value of a second function which is a function than the first function to the type specified thereto.