Comments on Sept Meeting Notes

Mark Miller erights at gmail.com
Thu Sep 26 22:36:18 PDT 2013


That's communicated information, not a communications channel. The passed
Symbol itself conveys that information, just as a passed string conveys
other information. The Symbol itself or the string must have arrived over a
communications channel, but that's another matter. If Alice conveys a
string or Symbol from Carol to Bob, she enables Carol to convey to Bob
whatever information Carol pre-packages into those bits. But this doesn't
enable further communication between Bob and Carol.

And the conveyance itself is only a one-way communication even of these
pre-packaged bits. Carol has no ability to tell that Bob received it, even
if Bob wishes to tell her.



On Thu, Sep 26, 2013 at 9:59 PM, Allen Wirfs-Brock <allen at wirfs-brock.com>wrote:

>
> On Sep 26, 2013, at 8:44 PM, Mark S. Miller wrote:
>
> I think an adequate registry is exactly the two static methods Allen
> proposed:
>
>  Symbol.for(aString) ==> aSymbol
>
>  Symbol.keyFor(aSymbol) ==> aString
>
> where for all strings S
>
>  Symbol.keyFor(Symbol.for(S)) === S
>
> I think we've discussed this before -- it is effectively an interning
> table for Symbols. The nice thing about it is that it is not a global
> communications channel at all. There's no way to tell if a given string or
> symbol has already been registered. The interning table can be weak or not
> as the implementation prefers.
>
>
> Well,   Symbol.keyFor(aSymbol) tells you whether or no aSymbol has been
> registered.  Of course, you have to have either created the symbol or had
> it passed to you in order to even make that test.  But jn the later case,
> would that make a 1-bit,  one-time communications channel back to other
> holders of the same symbol
>
> Allen
>
>
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>


-- 
Text by me above is hereby placed in the public domain

  Cheers,
  --MarkM
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