Type Systems for Programming Languages

1. Type Systems for Programming Languages Hongwei Xi University of Cincinnati Spring, 2000 Introduction

2. Welcome! • 20-ECES-717: Type Systems for Programming Languages • Introduction to type disciplines in programming language design and implementation • Emphasis on the use of mathematical methods in programming language studies Introduction

3. Course Overview • Type Systems • What is type safety? • What are the advantages of typed languages? • What are the disadvantages of typed languages? Introduction

4. Course Overview • Simply Typed Lambda-Calculus • Call-by-name and Call-by-value • Confluence Property (Church-Rosser) • Weak Normalization Theorem • Strong Normalization Theorem Introduction

5. Course Overview • Parametric Polymorphism • How can polymorphism facilitate code reuse? • How can polymorphism enforce data abstraction? Introduction

6. Course Overview • Subtyping • When is one type a subtype of another? • How can subtyping help code reuse? • Objects, Classes and Inheritance • How can we build flexible and extensible software? • How is subtyping related to inheritance? Introduction

7. Course Overview • Effects • References • Exceptions • Problematic interaction between polymorphism and effects • Value restriction Introduction

8. Course Overview • Continuation • callcc (call with current continuation) • throw • CPS compilation Introduction

9. Course Overview • Type Inference • Do types have to be obtrusive to programming? • Is it a good practice to omit writing types as much as possible? • What are the desirable properties in a type inference algorithm? Introduction

10. What is this course like? • Stressing both mathematical reasoning and implementation skill • Prove theorems • Build systems • Emphasizing mathematical rigor and clarity • “If you can’t explain it, I won’t trust it ” Introduction

11. What is this course like? • You will have to work hard in order to keep up! • Many ideas may sound unfamiliar to you. They are often formal and take time to “sink in”. • Assignments often require both mathematical reasoning and implementation skill. Introduction

12. What this course is like? • There is a draft textbook for this course on-line as well as some course notes • Taking notes is a large part of the course as we may often digress from the text book • Both studying and experimentation are essential to gaining understanding of the material Introduction

13. What is this course like? • Most of all, it’s a lot fun! • Elegant interplay between theory and practice • Rapid exposure to many fundamental ideas • Enormous potential for pursuing further studies in language design and implementation Introduction

14. Schedules • Lectures: MWF 12-12:50PM BH839 • Office Hours: • Thursday 4-6PM • Or by appointment (preferred) • Or stop by 811 D Rhodes Introduction

15. Programming Languages • Standard ML (preferred) • http://cm.bell-labs.com/cm/cs/what/smlnj • Objective Caml (preferred) • http://caml.inria.fr Introduction

16. Homework • Approximately 5 assignments • About one every two weeks • Individual work only unless specified otherwise! • Clarity and elegance count • It is not enough to just “work” on test data Introduction

17. Exams and Grades • Midterm • Monday, May 1 • In-class or Take Home (20%) • Final • Tuesday, June 6 • In-class or Take Home (40%) • Homework (40%) • All exams are open-book • Participation can make difference on letter grade Introduction

18. Academic Integrity • Strict adherence to the university guidelines • All work must be solely your own! • If you have difficulty keeping up, ask for help! • The instructor is always willing to help • Ask earlier, rather than later Introduction

19. Course Information • Everything is on the web! • Course Homepagehttp://www.ececs.uc.edu/~hwxi/eces717.html • Notes, Slides, Handouts, Assignments, Solutions • Please visit the homepage frequently! Introduction