On May 12, 2011, at 7:42 AM, Claus Reinke wrote:
>>>> ECMAScript has a large set of problems. ..
>>> - fixing ECMAScript's oddities would be worth a language revision, even
>>> without adding anything new
>> This is a mistake. The Web does not permit "stop the world and fix all known
>> bugs". Neither users nor competing browser or server-side software vendors
>> will stop.
>
> Ideals are like stars - out of reach, but good for orientation.
Bodies were heaped by the millions over the last few centuries in the name of
ideals. I detest _a priori_ systems that ignore empircal results. I don't buy
"ideal" without "real". Your message is woefully lacking in "real".
> The fixes alone would be worth a revision, and a competitive
> advantage (for language implementers and programmers,
> though the both would be limited by code having to work
> with other browsers). That ideal does not mean that language
> changes should not be introduced incrementally (refactoring
> beats rewriting). It only means that fixes can be as valuable
> as new features.
This is all vague sermonizing. Please stop.
There's a dream syntax Doug can glimpse (maybe I can too; working on it still)
that might be called a "fix". It relieves us of semicolons and ASI without
creating runtime migration traps.
Ok, show it. Or show a way to find it, a concrete method. The endless
ideal-mongering and vagueness don't cut it, and they are actually adding noise
and making trouble.
If we keep this up, we will have neither fixes (including the ones *in hand*,
e.g. lexical scoping) nor new features in ES.next.
>> We do not all even agree on what the problems are. The ones that we agree
>> on, we are successfully working on (modules, e.g.). Classes have had a rough
>> time because we don't even agree on premises or problems, never mind
>> conclusions or solutions.
>
> Douglas will speak for himself, I'm sure, but my own interpretation of his
> remarks was that most current work
> seems focused on extensions to the house, while there
> are some concerns about the foundation (not limited to
> functions).
Vague words, and where testable, precisely wrong. Lexical scope all the way
up, modules, let, const, some of the object initialiser extensions, and (I
argue) paren-free and the for-in reform it enables -- these are all fixes.
> Another way to look at it: independent of the concrete
> problems which you are working on, there seem to be
> some meta-level problems that keep coming up and
> get in the way of designing solutions. If that happens
> often enough, it may be worth stepping back and solve
> the meta-level problem first (no matter how horribly
> difficult to handle that elephant looks;-).
For me to keep parlaying here, you need to be specific or else stop injecting
so many generalizations which are either useless, or actually false when
applied to specifics I've listed above.
>> I'm working on better syntax, to present at the next TC39 meeting. I don't
>> think "perfect" is an option in this life. I'm aiming at "better".
>
> Better is the road to perfect.
No, there is no perfect. Get this right, or you are in dreamland (and I am
elsewhere).
>>> More concise function syntax is important, as long as the deeper issues get
>>> resolved, too.
>> What deeper issue beyond |this| binding (lexical, dynamic, soft, etc.) do
>> you mean, precisely?
>
> I don't yet have a complete enough overview for detailed language criticism,
> but I've been posting my concerns here as I encountered them.
> It would be good to have a process for registering information and
> suggestions with the committee and get feedback about the official reactions
> to such suggestions (an es-discuss bug tracker perhaps, separate from the
> spec bug tracker?).
>
> At this stage of my exploration, the main items seem to be:
>
> - expressions vs statements
> this is well-known and would be hard to fix (too big a change for
> javascript), beyond simplifying workarounds (such as parameterless
> functions as block "values");
Ok, so you say this is not realistically solvable. Why bring it up?
Next:
> - grammar
> too many details are hard-coded here: that makes the language
> complex and inflexible for the language design process (syntax
> should not get in the way as often as it does here), and
> limits language expressiveness for programmers (especially for
> abstraction providers); more of the changes that occupy
> TC39 should be possible at the level of libraries, not language;
You're arguing we can't improve the syntax of the language, even by extension?
False: let, const (already in browsers in a form that can be fixed), lexical
scope to get the global object off of the scope chain (this is an important
security fix), and modules.
Also: libraries are many and evolving, TC39 design-by-committee is about the
worst way to invent and evolve a library. We're de-facto standardizing (ES5 did
the Array extras, which still have some flaws we cannot fix).
> - program equivalences
> what equivalences hold for js code? Language implementers,
> tool builders, and programmers depend on being able to reason about code
> (optimizations, refactorings, code reading,
> maintenance, bug fixing);
>
> language-level equivalences are the most practical side of
> semantic tools: no need to reason about abstract machine
> details, or machine code, or mathematical constructs, just "this
> high-level code fragment is equivalent to that one"/
> "we can replace this with that and nothing will go wrong";
> obviously, reflection breaks all equivalences (which is one reason why
> mirrors and the like have been introduced: to delimit the code affected by
> reflection); but even without
> reflection interference, it seems difficult to find valid code
> equivalences for javascript;
(It's not that bad in practice once you [the refactoring entity] buy into
having to lex and parse everything. This seems a formal objection.)
> the more each instance of code has to be understood on its own -rather
> than by relation/equivalence/simplification, the more complex the language
> gets;
>
> it is great to have a detailed language spec (really! not all
> languages have one), but if we have to keep looking there, to understand
> why obvious code equivalences fail in javascript, the language becomes
> arcane (which is good for consultant experts, bad for everyone else);
This is long-winded and vague still (also badly formatted). What is your
specific, actionable point?
We can't lose statements with control effects without a big compatibility
break, and you ruled out new syntax above. Are you arguing against changing JS,
and for inventing a wholly new language?
Just yesterday I re-raised the {|a,b| a+b} Ruby/Smalltalk-inspired
block-as-lambda idea recently. It has the advantage of being concrete. It
preserves certain program equivalences at the price of creating new runtime
error conditions (return from an outer function call that has already returned,
e.g.). Please address it specifically, or make a competitive alternative
proposal.
> There are smaller items (some are instances of the above):
>
> - objects vs blocks; grammar ambiguities;
This is a glitch JS hackers I've surveyed informally simply learn and get past.
They don't even complain about it much, compared to lack-of-ASI (lack of
significant newline) traps. I've talked to many over the years.
Anyway, it is not going to be fixed without a new grammar, which you seem to
have ruled out above.
> - ASI coupling to combination of linebreak, error, restricted productions
> serves neither full-ASI nor no-ASI proponents,
> and complicates language extensions;
Yes, this is true and we've had proposals, including Mark's concrete proposal
for a better ASI and Harmony parsing both ways, declaring an early error on
disagreement. Unfortunately this requires backtracking and error recovery in a
"forked parser", so it looks too complicated for implementors *and* users, but
it was a concrete proposal in the right direction. Please do likewise and stop
rehashing the problem statement.
http://www.mail-archive.com/[email protected]/msg05606.html
> - mixing numeric indices and string properties (every object
> is an array, only Array instances have proper array methods);
> dynamic typing is much less problematic without implicit
> conversions muddying the waters;
I proposed tuples. They got a mixed reaction at the last tc39 meeting, and they
are not likely to get into ES.next at this point. Do you have anything to add
to this specific proposal, or another alternative specific proposal to make?
http://wiki.ecmascript.org/doku.php?id=strawman:tuples
> - var initializers shadow bindings in their rhs (similar to 'this'
> and 'arguments' shadowing, but worse through 'undefined');
> do we really need a different solution to each instance of
> shadowing problems? differences make for language
> complexity, extracting common solutions to common
> problems simplifies understanding;
This is a topic for let and const in blocks, which is still being debated
on-and-off. IIRC most of TC39 agreed to make let and const start a new implicit
scope, so an outer name could be used in the initialiser.
Again, we can't change var unless you want us to make incompatible changes,
which you seemed to advise against above. Which is it?
> - argument lists as arrays (instead of arrays as arguments)
> [this seems to be worked on];
It *is* being worked on, you should know that -- rest and spread are in harmony
-- yet you rehash and inject noise again here. Why? To channel Nancy Kerrigan:
WHYYYYY???? :-|
http://wiki.ecmascript.org/doku.php?id=harmony:rest_parameters
http://wiki.ecmascript.org/doku.php?id=harmony:spread
> - ephemeral nature of References; leads to syntactic junk in
> the language (syntactically valid code that predictably leads
> to runtime errors); also limits object methods as first-class
> values (they lose their base reference), breaks a dozen
> of "obvious" code equivalences (is this also behind direct
> vs indirect eval? I haven't checked yet);
This is not only a minor issue, truly small potatoes -- it is required for web
compatibility due to VBScript-tainted JScript of this kind:
d.items(i) = j;
That kind of crap exists in IE-only branches of JS on the web, so it must parse.
Let's focus on real problems affecting real users.
> - hardcoding of binary ops/precedences/associativity in grammar; these are
> much too variable to be written in stone, or be discussed by a language
> committee; for javascript to be adapted quickly to new domains, these
> should be in the hands of library authors and other abstraction providers;
>
> much too valuable a tool to ignore; if combined with
> lightweight function definition and application syntax,
> it helps in defining readable domain-specific languages;
>
> commonalities in embedded domain-specific languages
> feed back into general purpose control abstractions, which
> again should be provided in libraries (moving more quickly
> than language committees);
Sorry, we're not turning JS into Haskell or making the syntax, particularly the
operators, have adjustable precedence and associativity. This is not something
developers or implementors want. It has never been on the agenda, even for
value types/proxies. You are barking up the wrong tree here.
> Perhaps there were other items I don't recall right now (with a tracker, I
> could just look up my tickets, you could assign priorities, milestones, and
> committee members for those items you would want to adopt, and we'd all know
> where our suggestions stand).
>
>> I'll keep it short by stopping here. Precision in stating problems would be
>> appreciated.
>
> I hope this helps?
Not really.
I'm being rough on you here because we have a serious (serous enough, for a
discussion list I care about not going in ideal-mongering circles or filling
with useless noise and posturing) problem. We have real proposals for ES.next
on the table. They aren't all necessarily going to make it, but trying to reset
the discussion from them to vague ideals or non-issues like programmable
operator precedence does a disservice to our common effort here.
We need to get back to discussing the live strawman proposals, and refining the
proposals in harmony but not quite spec'ed fully. Will you help?
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