Hi HP
I already replied the "summary" email, but I think that here is an
important question as well for your understanding
HP Wei wrote:
[...]
Now, the question is
in the original snippet,
when C = {NewCell S} is executed,
S is an unbound name,
how does the system decide whether S is
a variable, a list or a list_with_future ??
At which step in the snippet does the decision
occur ?
The key concept is the variable, and you can bind it only once to a
stream, a list, a number, an atom, a cell, etc. Once is bound, you can't
change it. If you bind it to a cell, then, you can change the content of
the cell. For instance you can do:
proc {Foo Type Var}
if Type == cell then
Var = {NewCell foo}
elseif Type == stream then
Var = 1|2|3|4|_
else
Var = foo
end
end
So, the variable get its type dynamically.
cheers
Boriss
thanks
HP
On Mon, 12 Dec 2005, Boriss Mejias wrote:
declare P S in
local
Tag = {NewName}
fun {NewPort S}
C = {NewCell S} in
{NewChunk port(Tag:C)}
end
proc {Send P M}
Ms Mr in
{Exchange P.Tag Ms Mr}
%%% point C
Ms = M|Mr %%% point D
end
in
P = {NewPort S}
{Send P 1} %%% point A
{Send P 2} %%% point B
end
------------------------------------
At point A, S contains "1"|_
After point B, S contains "1"|"2"|_
Hi HP
Here is the confusion. When you sent 1 to the port in point A, you took
the variable S out of the cell, bind it to 1|Mr and put Mr into the
cell, then, Mr is the unbound tail of S.
So, what you always keep in the
cell, is the current unbound tail of S. I hope I can do a nice drawing
of this.
S = |
/ \
1 _ <---- C
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