Practical Foundations for Programming Languages

Types are the central organizing principle of the theory of programming languages. In this innovative book, Professor Robert Harper offers a fresh perspective on the fundamentals of these languages through the use of type theory. Whereas most textbooks on the subject emphasize taxonomy, Harper instead emphasizes genetics, examining the building blocks from which all programming languages are constructed. Language features are manifestations of type structure. The syntax of a language is governed by the constructs that define its types, and its semantics is determined by the interactions among those constructs. The soundness of a language design - the absence of ill-defined programs - follows naturally. Professor Harper's presentation is simultaneously rigorous and intuitive, relying on elementary mathematics. The framework he outlines scales easily to a rich variety of language concepts and is directly applicable to their implementation. The result is a lucid introduction to programming theory that is both accessible and practical. "Harper's book provides a comprehensive treatment of the foundations of computation. He touches on a surprising range of concepts that arise in language design: from simple types to polymorphism to dependent types to modules; from strict to lazy to parallel computation; and from proof techniques for reasoning about extensional behavior to practical, compositional cost models in the presence of garbage collection. More importantly, throughout the book he uses types and the principles of type theory to organize the material and help us discover the orthogonal, composable abstractions that arise naturally not only in the design of programming languages but also in logics and mathematics. This approach helps uncover the fundamental structure lurking inside programming languages of today, and provides a principled approach to the designs for tomorrow." Greg Morrisett, School of Engineering and Applied Sciences, Harvard University "Starting with a mathematically simple framework and organizing principles that give type systems a central role, Bob Harper's magnum opus reveals the theory of programming languages as a coherent scientific subject with both breadth and elegance. His enormous experience, pithy views, and great good taste are evident throughout a book that deserves to become a classic." Andrew Pitts, Computer Laboratory, University of Cambridge "This book offers an excellent introduction to a wide range of programming language concepts. They are all uniformly and carefully explained, using techniques that are very useful in practice for both analysis and implementation of programming languages. The book is authored by one of the most prominent researchers in type theory for programming languages. The presentation is very effective and based on the author's years of experience teaching the material." Lars Birkedal, Professor, IT University of CopenhagenPart I. Judgments and Rules: 1. Inductive definitions; 2. Hypothetical judgments; 3. Syntactic objects; 4. Generic judgments; Part II. Levels of Syntax: 5. Concrete syntax; 6. Abstract syntax; Part III. Statics and Dynamics: 7. Statics; 8. Dynamics; 9. Type safety; 10. Evaluation dynamics; Part IV. Function Types: 11. Function definitions and values; 12. Godel's system T; 13. Plotkin's PCF; Part V. Finite Data Types: 14. Product types; 15. Sum patterns; 16. Pattern matching; 17. Generic programming; Part VI. Infinite Data Types: 18. Inductive and co-inductive types; 19. Recursive types; Part VII. Dynamic Types: 20. The untyped 1-calculus; 21. Dynamic typing; 22. Hybrid typing; Part VIII. Variable Types: 23. Girard's system F; 24. Abstract types; 25. Constructors and kinds; 26. Indexed families of types; Part IX. Subtyping: 27. Subtyping; 28. Singleton and dependent kinds; Part X. Classes and Methods: 29. Dynamic dispatch; 30. Inheritance; Part XI. Control Effects: 31. Control stacks; 32. Exceptions; 33. Continuations; Part XII. Types and Propositions: 34. Constructive logic; 35. Classical logic; Part XIII. Symbols: 36. Symbols; 37. Fluid binding; 38. Dynamic classification; Part XIV. Storage Effects: 39. Modernized algol; 40. Mutable data structures; Part XV. Laziness: 41. Lazy evaluation; 42. Polarization; Part XVI. Parallelism: 43. Nested parallelism; 44. Futures and speculation; Part XVII. Concurrency: 45. Process calculus; 46. Current algol; 47. Distributed algol; Part XVIII. Modularity: 48. Separate compilation and linking; 49. Basic modules; 50. Parameterized modules; Part XIX. Equivalence: 51. Equational reasoning for T; 52. Equational reasoning for PCF; 53. Parametricity.