Andreas Rossberg wrote:
On 16 January 2012 23:18, David Herman<dher...@mozilla.com> wrote:
The goal that is missing, and what I believe is the single most
important part of my New Year's email, is:
9. Allow programmers to continue thinking of JS as a single
cohesive language.
This is a relative concept rather than an absolute one, but it has
real practical consequences on the overall cognitive complexity of
the language. If you look at the terminology we've been using in
TC39 for years, we either talk about multiple "modes" of JS, or
even talk about ES6 as if it's "the new language." I believe this
has been a mistake. Now, we've always agreed that ES6 must
necessarily subsume ES5. And you might claim that this was just
imprecise and casual speech, but I think it betrays a flawed
assumption: that ES6 gives us leeway to make clean breaks with the
past.
[...]
Instead, we should hew as close as possible to an ideal of One
JavaScript, knowing that we'll never be perfect. But -- I believe
-- we can get pretty darn close.
...
With your proposal, you give the current generation of programmers
the illusion that ES6 is a simple extension of ES5. But all future
programmers, who grow up with ES6 or beyond, will still have to deal
with the legacy of ES5 non-strict mode. There will be two modes to
worry about forever after (unless we make another breaking change).
Refactoring pitfalls will persist.
What I envision makes the transition somewhat more explicit for
current programmers (ideally, they need to write at most one extra
keyword). But anybody who starts development with ES6+ will never
have to care about modes again. For her/him, extended mode is all
that's relevant. Refactoring pitfalls only arise during initial
version transition.
I claim that on the long run, the latter will converge much closer
on the ideal of One JavaScript. With your proposal, you are
essentially trading perceived simplicity (which, as an aside, is
factual complexity) for current JS programmers for increased
complexity for all future JS programmers.
I agree with this. I think only a few things should be added to ES5
non-strict (destructuring, new object literal, .{...}, <| {...}, maybe
something more) and one and only one opt-in to ES6 should be module
{...}, eventually "use module;" or similar non-bracing implicit
module-wrapper form at the beginning of program (which can be trivially
taken care by concat-builders by wrapping such program in module { ...
}; it assume the "use module;" form is otherwise silently ignored inside
proper module and is syntax error outside it except as a first thing in
program). Nothing else (class in ES5 non-strict is syntax error etc.)
This keeps it simple and does not force you to move to ES6 for small
useful details, only for more serious new functionality.
You make a good point with JS code in HTML attributes, though. I
don't have a good answer for that, except falling back to a meta tag.
For that specific purpose, that might be fine.
/Andreas
Herby
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