Re: Paren-free heads strawman
Did you read the proposal?
http://wiki.ecmascript.org/doku.php?id=strawman:paren_free
Yes, it means if you start a condition with '(' you are obligated to use
paren-full not paren-free style. :-P
/be
On Mon, Feb 1, 2016 at 10:20 AM Andreas Rossberg
wrote:
> This refactoring hazard is intimately tied to the infinite look-ahead
> problem. Teaching a parser to handle the latter case or examples like `if
> (x) (y) -z {}` correctly is gonna be all but easy. Either backtracking or
> terrifying grammar refactorings would be needed.
>
> On 1 February 2016 at 18:46, Brendan Eich wrote:
>
>> On Mon, Feb 1, 2016 at 8:02 AM kdex wrote:
>>
>>> [Douglas Crockford](https://www.youtube.com/watch?v=Nlqv6NtBXcA) and
>>> [Brendan Eich](https://brendaneich.com/2010/11/paren-free/) seem
>>>
>>> to be in favor of making them optional; that's why the strawman exists.
>>>
>>>
>> The strawman exists because I wrote it, yes.
>>
>> I was inspired by the common (not ubiquitous) style of always bracing
>> sub-statements. The paren-free meme did "stick" with Rust, but it seems
>> doomed for JS on account of the problems Waldemar Horwat raised:
>>
>> https://esdiscuss.org/topic/another-paren-free-gotcha
>>
>> Not the cited example, that seemed to forget that paren-free requires
>> braces around the sub-statement in absence of leading left paren after
>> controlling keyword. I pointed this out here:
>>
>> https://esdiscuss.org/topic/another-paren-free-gotcha#content-9
>>
>> Waldemar's other example showed a refactoring hazard:
>>
>> """
>>
>> if (a + b/g > f) f = a + b/g
>>
>> Convert it to paren-free:
>>
>> if a + b/g > f {f = a + b/g}
>>
>> So far so good; it works. However, later someone discovers that the code
>> had a logic error, the fix to which is to divide the sum a+b by c instead
>> of dividing only b by c. So he fixes the code to:
>>
>> if (a + b)/g > f {f = (a + b)/g}
>>
>> """
>>
>> Anyway, the proposal predates 1JS (note my last message talks about "opt
>> in") and needs a champion who can resolve the refactoring hazard worry (if
>> possible).
>>
>> /be
>>
>> ___
>> es-discuss mailing list
>> es-discuss@mozilla.org
>> https://mail.mozilla.org/listinfo/es-discuss
>>
>>
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Re: Paren-free heads strawman
This refactoring hazard is intimately tied to the infinite look-ahead
problem. Teaching a parser to handle the latter case or examples like `if
(x) (y) -z {}` correctly is gonna be all but easy. Either backtracking or
terrifying grammar refactorings would be needed.
On 1 February 2016 at 18:46, Brendan Eich wrote:
> On Mon, Feb 1, 2016 at 8:02 AM kdex wrote:
>
>> [Douglas Crockford](https://www.youtube.com/watch?v=Nlqv6NtBXcA) and
>> [Brendan Eich](https://brendaneich.com/2010/11/paren-free/) seem
>>
>> to be in favor of making them optional; that's why the strawman exists.
>>
>>
> The strawman exists because I wrote it, yes.
>
> I was inspired by the common (not ubiquitous) style of always bracing
> sub-statements. The paren-free meme did "stick" with Rust, but it seems
> doomed for JS on account of the problems Waldemar Horwat raised:
>
> https://esdiscuss.org/topic/another-paren-free-gotcha
>
> Not the cited example, that seemed to forget that paren-free requires
> braces around the sub-statement in absence of leading left paren after
> controlling keyword. I pointed this out here:
>
> https://esdiscuss.org/topic/another-paren-free-gotcha#content-9
>
> Waldemar's other example showed a refactoring hazard:
>
> """
>
> if (a + b/g > f) f = a + b/g
>
> Convert it to paren-free:
>
> if a + b/g > f {f = a + b/g}
>
> So far so good; it works. However, later someone discovers that the code
> had a logic error, the fix to which is to divide the sum a+b by c instead
> of dividing only b by c. So he fixes the code to:
>
> if (a + b)/g > f {f = (a + b)/g}
>
> """
>
> Anyway, the proposal predates 1JS (note my last message talks about "opt
> in") and needs a champion who can resolve the refactoring hazard worry (if
> possible).
>
> /be
>
> ___
> es-discuss mailing list
> es-discuss@mozilla.org
> https://mail.mozilla.org/listinfo/es-discuss
>
>
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Re: Paren-free heads strawman
On Mon, Feb 1, 2016 at 8:02 AM kdex wrote:
> [Douglas Crockford](https://www.youtube.com/watch?v=Nlqv6NtBXcA) and
> [Brendan Eich](https://brendaneich.com/2010/11/paren-free/) seem
>
> to be in favor of making them optional; that's why the strawman exists.
>
>
The strawman exists because I wrote it, yes.
I was inspired by the common (not ubiquitous) style of always bracing
sub-statements. The paren-free meme did "stick" with Rust, but it seems
doomed for JS on account of the problems Waldemar Horwat raised:
https://esdiscuss.org/topic/another-paren-free-gotcha
Not the cited example, that seemed to forget that paren-free requires
braces around the sub-statement in absence of leading left paren after
controlling keyword. I pointed this out here:
https://esdiscuss.org/topic/another-paren-free-gotcha#content-9
Waldemar's other example showed a refactoring hazard:
"""
if (a + b/g > f) f = a + b/g
Convert it to paren-free:
if a + b/g > f {f = a + b/g}
So far so good; it works. However, later someone discovers that the code
had a logic error, the fix to which is to divide the sum a+b by c instead
of dividing only b by c. So he fixes the code to:
if (a + b)/g > f {f = (a + b)/g}
"""
Anyway, the proposal predates 1JS (note my last message talks about "opt
in") and needs a champion who can resolve the refactoring hazard worry (if
possible).
/be
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Re: Paren-free heads strawman
Braces required, see the old strawman. /be On Mon, Feb 1, 2016 at 9:18 AM Andreas Rossberg wrote: > Will > > if x (y) (z); > > parse as > > if (x) ((y)(z)); > > or > > if (x(y)) (z); > > ? And how do you parse it without infinite look-ahead? > > /Andreas > > > On 1 February 2016 at 17:01, kdex wrote: > >> Well, try and define "natural" in the context of constructed languages. >> >> If this was a question of "naturalness" (whatever that may be), then >> really any deviation from what the language currently is, is "unnatural". >> >> Anyway, we're here to discuss, not to blindly judge. :) >> >> >> >> Note that the parens serve no purpose whatsoever. >> >> They're actually just a relic dating back to Ken Thompson's >> re-interpretation of BCPL, B (1969), which in turn did this, because in >> FORTRAN, >> >> `if x` and `ifx` looked the same to the parser; the parens were thus >> needed for the parser to differentiate between the two. >> >> >> >> Since C derived from B, virtually any language that derived from it >> adapted to this redundant syntax; nowadays, the parens exist solely for >> decoration. >> >> >> >> [Douglas Crockford](https://www.youtube.com/watch?v=Nlqv6NtBXcA) and >> [Brendan Eich](https://brendaneich.com/2010/11/paren-free/) seem >> >> to be in favor of making them optional; that's why the strawman exists. >> >> >> >> On Montag, 1. Februar 2016 15:47:52 CET Alican Çubukçuoğlu wrote: >> >> > Isn't this very unnatural? If you are into this kind of thing, why don't >> >> > you code Coffee for example? (Or don't since saving a few keystrokes >> isn't >> >> > worth your dignity.) >> >> > >> >> ___ >> es-discuss mailing list >> es-discuss@mozilla.org >> https://mail.mozilla.org/listinfo/es-discuss >> >> > ___ > es-discuss mailing list > es-discuss@mozilla.org > https://mail.mozilla.org/listinfo/es-discuss > ___ es-discuss mailing list es-discuss@mozilla.org https://mail.mozilla.org/listinfo/es-discuss
Re: Paren-free heads strawman
I love the paren-free head idea. But as an obsessive user of non-braced
single-statement if/for/while bodies, I don't see the advantage of making
the head paren-free at the cost of mandating braces for the body.
Has either of the following been considered:
```js
if i < 3: foo();
if i < 3 do foo();
```
--
Bob
On Mon, Feb 1, 2016 at 4:43 PM, kdex wrote:
> I've noticed that there's a strawman that has been left untouched for
> quite a while, namely [strawman:paren_free](
> http://wiki.ecmascript.org/doku.php?id=strawman:paren_free).
>
> It intends to make parentheses in heads optional, making, for instance:
> ```js
> if x > 3 {
> /* … */
> }
> ```
>
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Re: Paren-free heads strawman
Will if x (y) (z); parse as if (x) ((y)(z)); or if (x(y)) (z); ? And how do you parse it without infinite look-ahead? /Andreas On 1 February 2016 at 17:01, kdex wrote: > Well, try and define "natural" in the context of constructed languages. > > If this was a question of "naturalness" (whatever that may be), then > really any deviation from what the language currently is, is "unnatural". > > Anyway, we're here to discuss, not to blindly judge. :) > > > > Note that the parens serve no purpose whatsoever. > > They're actually just a relic dating back to Ken Thompson's > re-interpretation of BCPL, B (1969), which in turn did this, because in > FORTRAN, > > `if x` and `ifx` looked the same to the parser; the parens were thus > needed for the parser to differentiate between the two. > > > > Since C derived from B, virtually any language that derived from it > adapted to this redundant syntax; nowadays, the parens exist solely for > decoration. > > > > [Douglas Crockford](https://www.youtube.com/watch?v=Nlqv6NtBXcA) and > [Brendan Eich](https://brendaneich.com/2010/11/paren-free/) seem > > to be in favor of making them optional; that's why the strawman exists. > > > > On Montag, 1. Februar 2016 15:47:52 CET Alican Çubukçuoğlu wrote: > > > Isn't this very unnatural? If you are into this kind of thing, why don't > > > you code Coffee for example? (Or don't since saving a few keystrokes > isn't > > > worth your dignity.) > > > > > ___ > es-discuss mailing list > es-discuss@mozilla.org > https://mail.mozilla.org/listinfo/es-discuss > > ___ es-discuss mailing list es-discuss@mozilla.org https://mail.mozilla.org/listinfo/es-discuss
Re: Paren-free heads strawman
Well, try and define "natural" in the context of constructed languages. If this was a question of "naturalness" (whatever that may be), then really any deviation from what the language currently is, is "unnatural". Anyway, we're here to discuss, not to blindly judge. :) Note that the parens serve no purpose whatsoever. They're actually just a relic dating back to Ken Thompson's re-interpretation of BCPL, B (1969), which in turn did this, because in FORTRAN, `if x` and `ifx` looked the same to the parser; the parens were thus needed for the parser to differentiate between the two. Since C derived from B, virtually any language that derived from it adapted to this redundant syntax; nowadays, the parens exist solely for decoration. [Douglas Crockford](https://www.youtube.com/watch?v=Nlqv6NtBXcA) and [Brendan Eich](https://brendaneich.com/2010/11/paren-free/) seem to be in favor of making them optional; that's why the strawman exists. On Montag, 1. Februar 2016 15:47:52 CET Alican Çubukçuoğlu wrote: > Isn't this very unnatural? If you are into this kind of thing, why don't > you code Coffee for example? (Or don't since saving a few keystrokes isn't > worth your dignity.) > ___ es-discuss mailing list es-discuss@mozilla.org https://mail.mozilla.org/listinfo/es-discuss
Re: Re: Paren-free heads strawman
Isn't this very unnatural? If you are into this kind of thing, why don't you code Coffee for example? (Or don't since saving a few keystrokes isn't worth your dignity.) ___ es-discuss mailing list es-discuss@mozilla.org https://mail.mozilla.org/listinfo/es-discuss
Paren-free heads strawman
I've noticed that there's a strawman that has been left untouched for quite a
while, namely
[strawman:paren_free](http://wiki.ecmascript.org/doku.php?id=strawman:paren_free).
It intends to make parentheses in heads optional, making, for instance:
```js
if x > 3 {
/* … */
}
```
equivalent to:
```js
if (x > 3) {
/* … */
}
```
Does anyone know if there are still any efforts to bring this into a future
version of EcmaScript?
The strawman hasn't been updated for five years, and I have the feeling that
this addition was forgotten about.
The last time I've heard anyone from TC39 talk about paren-free heads was at
[GOTO Aarhus 2013](https://www.youtube.com/watch?v=Nlqv6NtBXcA).
Note that the strawman also talks about backward compatibility:
> For backward compatibility, we support parenthesized heads with any
> sub-statement. To preserve the LR(1) grammar this requires factoring out
> OtherStatement.
>
> Thus, this proposal is intended to make no backward-incompatible syntactic or
> semantic changes to ES5. “Paren-free” is now > purely a relaxation of syntax
> rules.
If anyone seeks to try this out, Mozilla's
[Narcissus](https://github.com/mozilla/narcissus/) has been supporting it for
years now. You can enable it via `--paren-free`.
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Paren-free heads strawman
I've noticed that there's a strawman that has been left untouched for quite a
while, namely
[strawman:paren_free](http://wiki.ecmascript.org/doku.php?id=strawman:paren_free).
It intends to make parentheses in heads optional, making, for instance:
```js
if x > 3 {
/* … */
}
```
equivalent to:
```js
if (x > 3) {
/* … */
}
```
Does anyone know if there are still any efforts to bring this into a future
version of EcmaScript?
The strawman hasn't been updated for five years, and I have the feeling that
this addition was forgotten about.
The last time I've heard anyone from TC39 talk about paren-free heads was at
[GOTO Aarhus 2013](https://www.youtube.com/watch?v=Nlqv6NtBXcA).
Note that the strawman also talks about backward compatibility:
> For backward compatibility, we support parenthesized heads with any
> sub-statement. To preserve the LR(1) grammar this requires factoring out
> OtherStatement.
>
> Thus, this proposal is intended to make no backward-incompatible syntactic or
> semantic changes to ES5. “Paren-free” is now > purely a relaxation of syntax
> rules.
If anyone seeks to try this out, Mozilla's
[Narcissus](https://github.com/mozilla/narcissus/) has been supporting it for
years now. You can enable it via `--paren-free`.
___
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