concurrency.md

@@ -27,6 +27,7 @@ Papers and other docs:
 - [ Extending the Haskell FFI with Concurrency](http://www.haskell.org/~simonmar/papers/conc-ffi.pdf) (a specification of the interaction between concurrency and the FFI, with a semantics)
 - [ A Draft report addendum](http://www.haskell.org/ghc/docs/papers/threads.ps.gz) (a shorter version of the above paper).
 - [ Software Transactional Memory](http://research.microsoft.com/~simonpj/papers/stm/)
+- [ State Threads for C](http://state-threads.sourceforge.net/)
 
 ---
 
@@ -34,7 +35,7 @@ Papers and other docs:
 # Proposal
 
 
-## what is provided
+## what is required by the standard
 
 
 
@@ -68,6 +69,12 @@ Additionally, we have a fairness property of `MVar`s:
 This means that `MVar` blocking must be implemented in a fair way, eg. a FIFO of blocked threads.
 
 
+
+In order to meet the progress guarentee, an implementation must yield to
+another thread, waiting for an appropriate event, before any action that
+entails blocking for an indeterminate amount of time. 
+
+
 ## `MVar` Guarentees
 
 
@@ -163,6 +170,15 @@ The implementation additionally allows the following:
 - bound threads: `forkOS`, `isCurrentThreadBound`, `runInBoundThread`, `runInUnboundThread`
 - concurrent/reentrant foreign calls are supported
 
+# Notes - Sharing
+
+
+
+Although not mentioned in the standard, the use of Concurrency may affect
+the lazy sharing of computations. Consult an implementations documentation if
+this might be an issue for you.
+
+
 # Status of Compilers