We now consider specification and construction techniques tailored to a particular application domain: code that is intended to test whether arbitrary input strings may be matched by a specific “pattern.” The pattern itself is essentially the specification for such a program, and a variety of specialized notations and implementation techniques have been developed to allow convenient expression and realization of such specifications. Although the methods are specialized to the application, the key principles of formal methods—distinguishing between specification and realization, adopting appropriate formalized notation for specifications, and using systematic or verifiable methods of program construction—are still relevant. Chapter 7 introduces the basic concepts, and Chapters 8 to 11 discuss various styles of pattern specification and how they may be systematically transformed and realized.

Additional Reading

Many books cover this material, usually from either a primarily theoretical perspective [HU79, MAK88, LP98] or a compiler-oriented one [ASU86]; [Gou88, AU92, HMU01] are closest to the approach adopted here.