||The semantics of programs written in some languages is concerned with
the interpretation in various types of models. We present a new approach
to semantics: behavior of programs, i.e. changes of states is modeled in
the category of states. Category morphisms express elementary execution
steps and program execution is an oriented path in the category, i.e.
composition of morphisms. Our categorical model is constructed for a
simple procedural language that contains all basic van Dijkstra's
constructs. We enrich our approach also with procedures forming a
collection of categories interconnected by functors. This method enables
the repeated call of procedures, nesting of procedure calls and
recursive calls. Moreover, it allows us to illustrate and accentuate
dynamics of program execution.