1. Programming Languages:Design, Specification, and Implementation G22.2210-001 Rob Strom November 9, 2006

2. Other readings on ML http://www.dcs.ed.ac.uk/home/stg/NOTES/notes.html

3. Readings (week 1) • Theoretical and Historical Papers on Concurrency • The “Readers/Writers” Problem http://www.md.chalmers.se/~ptrianta/SynC+Co/LIT/lamp77.pdf.gz • Shared Registers (Part II) http://users.ece.gatech.edu/~dblough/6102/lamport_consistency.pdf • Wait-free synchronization http://www.cs.brown.edu/~mph/Herlihy91/p124-herlihy.pdf • Partially-ordered time. http://research.microsoft.com/users/lamport/pubs/time-clocks.pdf • Concurrency models in object-oriented languages • Ada Reference Manual Section 9 • Java Reference Manual Chapter 17 • Thinking in C++, chapter 11 • http://web.mit.edu/merolish/ticpp/TicV2.html#_Toc53985862

4. Readings (week 2) • Problems with the Memory Model • Java Memory model is Broken http://www.cs.umd.edu/~pugh/java/broken.pdf • Thread-Safe Programming • Compiler-Enforced Thread-Safety (Guava): http://researchweb.watson.ibm.com/people/d/dfb/papers/Bacon00Guava.ps • Safe Reader-Writer Parallelism (Optimistic Readers): http://www.research.ibm.com/distributedmessaging/paper13.html

5. Programming Project on Concurrency – due Nov. 30 • Extend the room world of the previous assignment so that multiple people can enter rooms and do things • Each thing someone does is an atomic unit of work, e.g. • Get things from factories and put them in the room • Pick up a bunch of objects and put them in a container • Pick up 2 containers and a funnel and transfer liquid from one container to the other • Don’t deadlock • Anticipate contention – e.g. you’ve picked up object A and try to pick up object B, but discover it’s gone because someone else picked up object B. You may need to give up your scripted action. • The implementation should have the same realism properties as the non-concurrent implementation did: e.g. things shouldn’t spontaneously disappear or appear in multiple places. • You may use any one of C++, Java, or Ada (probably the same language you used for previous assignment, but this is not required)

6. Notes on Grading of Projects • The bulk of the points should go for understanding the assignment and correctly using the features of the languages being tested (e.g. in the polymorphism assignment, triggering run-time dispatching, and sharing a common interface). • The next group of points is for clear documentation of the components, and what they do. • The last group of points should be for correctness, freedom from bugs, conformity to test cases.

7. Homework:ML Type Inference Problem • Type inference: fun zip f nil nil = nil | zip f (h::t) (i::s) = f(h,i)::zip f t s; What does it do? What is its most general type? • Consider these two expressions (1) fun f g = g 7 + g false; (2) let val g = fn (x) => 20 in g 7 + g false; Why is (1) incorrectly typed and (2) correctly typed? What is the type of g in (2)?