implementing a future in lua

["李慧霸" <magazine.lihuiba@...>]

Hi,

I'm doing research on language constructs. And I'm going
to implement a Future mechanism in lua (taking lua as a
testbed). The Future mechanism can be introduced as:

"The construct (future X) immediately returns a future for 
the value of the expression X and concurrently begins evaluating
X. When the evaluation of X yields a value, that value replaces 
the future. The future is said to be initially undetermined; it 
becomes determined when its value has been computed. An operation 
(such as addition) that needs to know the value of an undetermined 
future will be suspended until the future becomes determined, but 
many operations, such as assignment and parameter passing, do not 
need to know anything about the values of their operands and may 
be performed quite comfortably on undetermined futures. The use of 
futures often exposes surprisingly large amounts of parallelism in 
a program…"

As I'm only a beginer of lua and I'm not familiar with its VM 
implementation, can anyone here give me some advice? Thank you!
I have read some documents and the source code, and will begin writing.


And I wonder whether is there an interest of adding this feature to 
lua. There seems to be little modification to the language itself, 
all that is needed to do lies in the VM and library routines only. So
the future construt is not likely to break existing code.
 				
--------------
lihuiba
2008-12-27