On Nov 11, 2011, at 9:13 AM, David Herman wrote:
> On Nov 11, 2011, at 8:19 AM, Mark S. Miller wrote:
>
>> On Fri, Nov 11, 2011 at 7:40 AM, gaz Heyes <gazhe...@gmail.com> wrote:
>> On 11 November 2011 15:33, Mark S. Miller <erig...@google.com> wrote:
>> let a = ({
>>
>> print('doing stuff');
>> 100;
>> });
>>
>> How do you know the difference between a blank block statement and a object
>> literal? Surely it becomes an expression once an assignment occurs anyway.
>>
>> Doh! Sorry, I completely mis-thought that. Nevermind.
>
> Your idea of mandatory parens is still valid (if, IMO, a bit unsatisfyingly
> verbose) for most statement forms. It's only the block-statement-expression
> that doesn't work. Hence my do-expressions:
>
> http://wiki.ecmascript.org/doku.php?id=strawman:do_expressions
>
> or Brendan's subtly-disambiguated-block-statement-expressions:
>
> http://wiki.ecmascript.org/doku.php?id=strawman:block_vs_object_literal
>
> If Brendan's idea can be made to work, and it's not too confusing, I'm pretty
> sure I'd prefer it over do-expressions.
I think you''d be making a mistake to go in that direction. do-expression is a
very good solution that fits very well into the language and does not introduce
any new readability ambiguities (coining a phrase, a readability ambiguity is a
construct that is not formally ambiguous according to the grammar but which
will require mental effort by a human reader to appropriate classify).
> You could simply write:
>
> let a = {
> print('doing stuff');
> 100
> };
>
> How gorgeous is that?
not very... when I see a = { I immediate have to start thinking, is this think
that follows the =? Is it block expression? is it an object literal? is it a
block lambda?
but if I see any of:
let a = do {...
let a = {|| ...
let a = { ...
I immediately know what follows. That is gorgeous...
>
> But I suspect as we work on evolving the syntax of object literals, it'll get
> harder to keep them disambiguated. For example, is this:
we're already there ...
>
> let a = {
> foo(x)
> {
> alert(x)
> }
> }
>
> ...equivalent to this?
>
> let a = {
> foo: function(x)
> {
> alert(x);
> }
> };
>
> ...or this?
>
> let a = {
> foo(x);
> {
> alert(x);
> }
> };
>
> So I just don't know if it's feasible.
And being technically feasible does not make it desirable. Just remember the
phrase: "readability ambiguity"
Allen
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