This article describes a new approach to hardware-software codesign using high-level programming languages, such as C++, Java, Ada or Scheme. Unlike previous approaches, the designer may choose the model of computation and the specification languafe thar best suits her needs, while still being able to formally verify the correctness of the specification. The details of the available hardware and software resources, and the implementation of the different models of computation are encapsulated in libraries to maximize reuse in system specifications.