A course in computer programming provides the typical student's first exposure to the field of computer science. Most students in such a course will have used computers all their lives, for email, games, web browsing, word processing, social networking, and a host of other tasks, but it is not until they write their first programs that they begin to appreciate how applications work. After gaining a certain level of facility as programmers (presumably with the help of a good course in data structures and algorithms), the natural next step is to wonder how programming languages work. This book provides an explanation. It aims, quite simply, to be the most comprehensive and accurate languages text available, in a style that is engaging and accessible to the typical undergraduate. This aim reflects my conviction that students will understand more, and enjoy the material more, if we explain what is really going on.

In the conventional "systems" curriculum, the material beyond data structures (and possibly computer organization) tends to be compartmentalized into a host of separate subjects, including programming languages, compiler construction, computer architecture, operating systems, networks, parallel and distributed computing, database management systems, and possibly software engineering, object-oriented design, graphics, or user interface systems. One problem with this compartmentalization is that the list of subjects keeps growing, but the number of semesters in a Bachelor's program does not. More important, perhaps, many of the most interesting discoveries in computer science occur at the boundaries between subjects. The RISC revolution, for example, forged an alliance between computer architecture and compiler construction that has endured for 25 years. More recently, renewed interest in virtual machines has blurred the boundaries between the operating system kernel, the compiler, and the language run-time system. Programs are now routinely embedded in web pages, spreadsheets, and user interfaces. And with the rise of multicore processors, concurrency issues that used to be an issue only for systems programmers have begun to impact everyday computing.