This text developed out of our experiences teaching courses covering the formal semantics of programming languages. Independently we both developed laboratory exercises implementing small programming languages in Prolog following denotational definitions. Prolog proved to be an excellent tool for illustrating the formal semantics of programming languages. We found that these laboratory exercises were highly successful in motivating students since the hands-on experience helped demystify the study of formal semantics. At a professional meeting we became aware of each other’s experiences with a laboratory approach to semantics, and this book evolved from that conference.
Although this text has been carefully written so that the laboratory activities can be omitted without loss of continuity, we hope that most readers will try the laboratory approach and experience the same success that we have observed in our classes.
We have pursued a broad spectrum of definitional techniques, illustrated with numerous examples. Although the specification methods are formal, the presentation is “gentle”, providing just enough in the way of mathematical underpinnings to produce an understanding of the metalanguages. We hope to supply enough coverage of mathematics and formal methods to justify the definitional techniques, but the text is accessible to students with a basic grounding in discrete mathematics as presented to undergraduate computer science students.
There has been a tendency in the area of formal semantics to create cryptic, overly concise semantic definitions that intimidate students new to the study of programming languages. The emphasis in this text is on clear notational conventions with the goals of readability and understandability foremost in our minds.
As with other textbooks in this field, we introduce the basic concepts using mini-languages that are rich enough to illustrate the fundamental concepts, yet sparse enough to avoid being overwhelming. We have named our minilanguages after birds.