concurrency.md

@@ -48,3 +48,41 @@ Questions:
 
 - Require bound thread support, or make it optional?  (YHC has concurrency with non-blocking foreign calls, but doesn't
   have bound threads as yet.)
+
+---
+
+# Levels
+
+
+There are several levels of concurrency support which require sucessivly more
+implementation support and imply more implementation overhead.
+
+## No Concurrency
+
+
+The report says nothing about concurrency at all
+
+## Concurrent Friendly
+
+
+Enough is specified to allow people to write completley portable programs and
+libraries that while they may not depend on concurrency, will not break in the
+presence of it. 
+
+
+This would entail
+
+- A standardized MVar-like structure.
+- something along the lines of [ForeignBlocking](foreign-blocking)
+
+## Concurrent Capabale
+
+
+This would allow concurrency needing programs to be written, but perhaps not
+as transparently as it curently is with GHC. This would include everything
+needed to write concurrent programs without anything that would imply a
+run-time or implementation overhead in the non-concurrent case. 
+
+## Concurrent Built-in
+
+## Concurrent Preemptive/SMP
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