Programming-in-the large versus programming-in-the-small

We distinguish the activity of writing large programs from that of writing small ones. By large programs we mean systems consisting of many small programs (modules), possibly written by different people. We need languages for programming-in-the-small, i.e. languages not unlike the common programming languages of today, for writing modules. We also need a “module interconnection language” for knitting those modules together into an integrated whole and for providing an overview that formally records the intent of the programmer(s) and that can be checked for consistency by a compiler. We explore the software reliability aspects of such an interconnection language. Emphasis is placed on facilities for information hiding and for defining layers of virtual machines.