On 11.11.2011 21:13, 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
<mailto:gazhe...@gmail.com>> wrote:
On 11 November 2011 15:33, Mark S. Miller <erig...@google.com
<mailto: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. You could simply write:
let a = {
print('doing stuff');
100
};
If we write so in e.g. if-expression (which actually uses the same
*block*), then by logic we should write the same in a simple (and the
same) *block*:
// conditional evaluation of `a`
let a = if (true) { 10 } else { 20 }
// unconditional evaluation of `a`
let a = {10}
(BTW, everyone already now may test it -- as Dave noted, you may use
`eval` to get the completion type of a statement; moreover, you may
write a simple parser which just replaces all such expressions with
`eval`s -- not for production sure, but for tests: let a = eval('if
(true) {10} else {20}'); console.log(a) -- 10)
OTOH, if there will be unresolvable (?) issues with grammar, etc, we may
of course adopt a special syntax of eval'ing such simple blocks,
unfortunately regardless, that e.g. in `if` which uses the same block we
may write it easily and directly.
How gorgeous is that?
It's normal and consistent with other blocks, I'd say.
Dmitry.
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:
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.
Dave
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