[Laszlo-dev] The one thing I really miss from Lisp is symbols

[Henry Minsky]

Yeah I wish it was in the JSON reader, otherwise there's no way to do the
interning automatically  unless you use eval.

On 1/5/07, P T Withington <ptw at openlaszlo.org> wrote:
>
> On 2007-01-05, at 10:32 EST, Henry Minsky wrote:
>
> > I was looking at a JSON (www.json.org) specification , and I
> > realized one
> > thing I miss in
> > programming languages these days are symbols. JSON is pretty close
> > to an
> > s-expression except for
> > the lack of symbols (except for the special cases of 'true',
> > 'false', and
> > 'null').
> >
> > None of the popular  scripting languages
> > seem to have symbols. You'd think wth the interest in JSON that
> > people might
> > start wondering
> > if there is some way to have built-in interned strings supported by
> > their
> > language...
>
> Well, Objects have most of the features of symbols:  they are unique,
> you can compare them for identity, you can store properties on them.
> An object by itself is like an uninterned symbol -- you have to keep
> a handle on it.  If you want to intern an object, you can just assign
> it to a global variable.  So, I think what you are mostly missing is
> the shorthand where in lisp you can write `:foo` and if the symbol
> already exists, you get the symbol, and if it doesn't it will be
> created for you.
>
> It wouldn't take much to mimic that in Javascript.  Something like:
>
> class _ {
>    static var allSymbols = {};
>
>    function _(name) {
>      if (name in _.allSymbols) return _.allSymbols[name];
>      this._name = name;
>      return _.allSymbols[name] = this;
>    }
>
>    function toString() {
>      return this._name;
>    }
> }
>
> Then you can write a symbol as:
>
>    _('mySymbol')
>
> Clearly, IWBNI there were a shorter hand for writing symbol literals,
> 1 character rather than 5, but this isn't too bad is it?
>
>


-- 
Henry Minsky
Software Architect
hminsky at laszlosystems.com
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