On Sep 29, 2011, at 10:07 PM, Sean Eagan wrote:
> On Thu, Sep 29, 2011 at 3:30 PM, Brendan Eich <[email protected]> wrote:
>
>> The idea is that sealing an object is more common than freezing it, while
>> freezing a property is more common than sealing it.
>
> I was thinking freezing an object is more common than sealing, but #
> for freeze, ## for seal looks backwards anyways.
Yes, if we allow doubling then obviously two is colder than one ;-). But should
we allow doubling? I was arguing against, on the basis that one ugly character
is enough for the common case. This led to the irregular but use-case oriented
(we think -- you could be right, we haven't measured and not enough code uses
ES5 freeze and seal) consensus Waldemar reported.
>
>> We don't want # as a prefix for value types.
>
> Agree, but why not for at least Arrays if not Functions and Regexps as well ?
What about the function's .prototype object? Would that be sealed or frozen
too? Perhaps not.
How about lastIndex updating on a #/.../g regexp?
> Probably shouldn't have <| for value types either then right ?
That's right, they are not objects.
>
>>> Compose with <|:
>>>
>>> null <| ##{...} // record-esque
>>> null <| ##[...] // tuple-esque
>>
>> These are too long if common, they want the HoMD single # prefixing.
>
> Agree. I think composition with <| still is needed though for
> consistency with non-#-prefixed literals if nothing else.
It should work -- at first it looks like evaluation order will result in <|
cloning the sealed (at least) RHS and then try to update its [[Prototype]], but
that seems legal. [[Extensible]] = false does not prevent internal properties
from changing. Should check with Allen on this, though.
>
>>> Include tuple-isms for #[], ##[]:
>>>
>>> holes => syntax error
>>> length cannot be greater than 2^32 - 1
>>
>> Sure, this carries over for all tuple proposals (I assert). But we want
>> shorter syntax, no doubled funny chars, no verbose regularity at the expense
>> of common cases being relatively overlong.
>
> So if #[] is added as shorthand for a sealed Array, do you agree that
> #[0,,1] should be a syntax error ?
I thought I just said so ("Sure, this carries over for all tuple proposals" in
reply to your "holes => syntax error").
/be
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