Re: [PHP-DEV] Re: [RFC][DISCUSSION] Match expression v2
On Tue, 23 Jun 2020 at 09:54, Björn Larsson
wrote:
>
> Ok, thanks for the clarification. The reason for me to bring
> this up is that I was pondering on if this is the only place in
> PHP where a semicolon is required after a curly bracket
> when not used in an expression.
>
Two things:
- as proposed here, match is *always* an expression; it just happens that
PHP lets you throw away the result of an expression, so "match($x){};" is a
valid statement for the same reason "42;" is a valid statement
- as Ilija mentioned, ending a statement with an anonymous function also
leads to the combination "};"
function returnsFunc() {
return function() { echo "Hello, world!\n"; };
}
function returnsMatchResult($x) {
return match($x) { 1=> "Hello", 2=>"world" };
}
I'd also note that while there aren't currently many cases where it would
be ambiguous whether a statement or expression was intended, new ones might
be added in future. For instance, post-fix conditionals (like in Perl and
Ruby) would give us match($x) { ... } if $condition;
This kind of syntax short-cut tends to end up with complex rules of "it's
optional except when it's not", which I'm personally not a fan of.
Regards,
--
Rowan Tommins
[IMSoP]
Re: [PHP-DEV] Re: [RFC][DISCUSSION] Match expression v2
Den 2020-06-23 kl. 10:30, skrev Ilija Tovilo:
Hi Björn
I'd like to announce the match expression v2 RFC:
https://wiki.php.net/rfc/match_expression_v2
Absolutely so. I was thinking of the case mentioned in v1 RFC when it's used
as a stand-alone expression.
match ($y) {
...
};
` Optional?
In this RFC the semicolon is required. Many people thought the grammar
rules for the optional semicolon were confusing which is why I dropped
that feature in this RFC.
Ilija
Ok, thanks for the clarification. The reason for me to bring
this up is that I was pondering on if this is the only place in
PHP where a semicolon is required after a curly bracket
when not used in an expression.
If so I a counter argument could that it it is confusing for
programmers, not so privy to all the ins and outs of PHP.
Anyway, maybe a feature to consider for a future 8.1 RFC.
r//Björn
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Re: [PHP-DEV] Re: [RFC][DISCUSSION] Match expression v2
Hey,
On Tue, Jun 23, 2020, 11:34 AM Ilija Tovilo wrote:
> Hi Benas
>
> >> I'd like to announce the match expression v2 RFC:
> >> https://wiki.php.net/rfc/match_expression_v2
>
> > Then it's not a standalone expression but a block. In this case, you
> cannot add an optional semicolon at all.
> >
> > But this RFC v2 is not proposing to add a block, therefore you won't be
> allowed to use `match` construct as a standalone expression anyways.
>
> Using match as a standalone expression is definitely allowed, just
> like any other expression.
>
> // This is fine, the semicolon is required
> match ($foo) {
> $bar => baz(),
> };
>
Yup but it won't return you out of the function. For example, this wouldn't
work:
```
function test(int $value): bool {
match($value) {
0 => false,
1 => true
}
}
$test = test(1);
```
But it seems by standalone expressions, Bjorn meant your example. Sorry for
the confusion, I thought he was referring to blocks.
> Ilija
>
> --
> PHP Internals - PHP Runtime Development Mailing List
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>
>
Re: [PHP-DEV] Re: [RFC][DISCUSSION] Match expression v2
Hi Benas
>> I'd like to announce the match expression v2 RFC:
>> https://wiki.php.net/rfc/match_expression_v2
> Then it's not a standalone expression but a block. In this case, you cannot
> add an optional semicolon at all.
>
> But this RFC v2 is not proposing to add a block, therefore you won't be
> allowed to use `match` construct as a standalone expression anyways.
Using match as a standalone expression is definitely allowed, just
like any other expression.
// This is fine, the semicolon is required
match ($foo) {
$bar => baz(),
};
Ilija
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Re: [PHP-DEV] Re: [RFC][DISCUSSION] Match expression v2
On Tue, Jun 23, 2020, 11:23 AM Björn Larsson
wrote:
> Den 2020-06-22 kl. 18:05, skrev Benas IML:
>
> > On Mon, Jun 22, 2020, 6:35 PM Björn Larsson
> > wrote:
> >
> >> Hi Ilija,Den 2020-06-18 kl. 22:51, skrev Ilija Tovilo:
> >>
> >>> Hi Björn
> >>>
> > I'd like to announce the match expression v2 RFC:
> > https://wiki.php.net/rfc/match_expression_v2
> Well one could argue that when working with legacy code containing
> switch statements where one gradually migrates to match, it might be
> easier to have the same separator, i.e. ":".
> >>> I think that's somewhat of a moot point. The syntax of match is quite
> >>> different (match instead of switch, no case, no break, colon instead
> >>> of case, comma instead of semicolon, trailing semicolon). Just making
> >>> one of those the same doesn't make a meaningful difference for ease of
> >>> migration.
> >> Agree on that! One thing though. Is semicolon mandatory or is it
> optional
> >> like in the first RFC? Feels a bit odd with a semicolon after a curly
> >> bracket.
> >>
> > It's mandatory since it's an expression, not a block. Another example of
> an
> > expression would be a closure:
> >
> > ```
> > $fn = function () {
> > ...
> > }; // a semicolon is mandatory here.
> > ```
>
> Absolutely so. I was thinking of the case mentioned in v1 RFC when it's
> used
> as a stand-alone expression.
> match ($y) {
> ...
> };
>
Then it's not a standalone expression but a block. In this case, you cannot
add an optional semicolon at all.
But this RFC v2 is not proposing to add a block, therefore you won't be
allowed to use `match` construct as a standalone expression anyways.
` Optional?
>
> r//Björn L
>
Re: [PHP-DEV] Re: [RFC][DISCUSSION] Match expression v2
Hi Björn
>> I'd like to announce the match expression v2 RFC:
>> https://wiki.php.net/rfc/match_expression_v2
> Absolutely so. I was thinking of the case mentioned in v1 RFC when it's used
> as a stand-alone expression.
> match ($y) {
> ...
> };
> ` Optional?
In this RFC the semicolon is required. Many people thought the grammar
rules for the optional semicolon were confusing which is why I dropped
that feature in this RFC.
Ilija
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Re: [PHP-DEV] Re: [RFC][DISCUSSION] Match expression v2
Den 2020-06-22 kl. 18:05, skrev Benas IML:
On Mon, Jun 22, 2020, 6:35 PM Björn Larsson
wrote:
Hi Ilija,Den 2020-06-18 kl. 22:51, skrev Ilija Tovilo:
Hi Björn
I'd like to announce the match expression v2 RFC:
https://wiki.php.net/rfc/match_expression_v2
Well one could argue that when working with legacy code containing
switch statements where one gradually migrates to match, it might be
easier to have the same separator, i.e. ":".
I think that's somewhat of a moot point. The syntax of match is quite
different (match instead of switch, no case, no break, colon instead
of case, comma instead of semicolon, trailing semicolon). Just making
one of those the same doesn't make a meaningful difference for ease of
migration.
Agree on that! One thing though. Is semicolon mandatory or is it optional
like in the first RFC? Feels a bit odd with a semicolon after a curly
bracket.
It's mandatory since it's an expression, not a block. Another example of an
expression would be a closure:
```
$fn = function () {
...
}; // a semicolon is mandatory here.
```
Absolutely so. I was thinking of the case mentioned in v1 RFC when it's used
as a stand-alone expression.
match ($y) {
...
};
` Optional?
r//Björn L
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Re: [PHP-DEV] Re: [RFC][DISCUSSION] Match expression v2
On Mon, Jun 22, 2020, 6:35 PM Björn Larsson
wrote:
> Hi Ilija,Den 2020-06-18 kl. 22:51, skrev Ilija Tovilo:
>
> > Hi Björn
> >
> >>> I'd like to announce the match expression v2 RFC:
> >>> https://wiki.php.net/rfc/match_expression_v2
> >> Well one could argue that when working with legacy code containing
> >> switch statements where one gradually migrates to match, it might be
> >> easier to have the same separator, i.e. ":".
> > I think that's somewhat of a moot point. The syntax of match is quite
> > different (match instead of switch, no case, no break, colon instead
> > of case, comma instead of semicolon, trailing semicolon). Just making
> > one of those the same doesn't make a meaningful difference for ease of
> > migration.
> Agree on that! One thing though. Is semicolon mandatory or is it optional
> like in the first RFC? Feels a bit odd with a semicolon after a curly
> bracket.
>
It's mandatory since it's an expression, not a block. Another example of an
expression would be a closure:
```
$fn = function () {
...
}; // a semicolon is mandatory here.
```
>> Is the proposed => separator inspired by Rust or Scala? Checked what
> >> other languages used and for switch it's ":" of course. So one might
> >> argue that to align with match statements in other languages "=>" is
> >> a good choice, but OTOH if ones sees match as an enhanced switch,
> >> having ":" as a separator is another alternative.
> > Since nobody else asked for it, just for you I compiled a list of
> > other languages :)
> >
> > https://gist.github.com/iluuu1994/11ac292cf7daca8162798d08db219cd5
> >
> > The conclusion: Most languages also use some form of arrow. It makes
> > sense to me to stay consistent with those languages.
> >
> > Ilija
>
> I think this is a very good motivation on why select => as a symbol and
> I'm glad it's listed in the RFC.
>
> r//Björn
>
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>
>
Re: [PHP-DEV] Re: [RFC][DISCUSSION] Match expression v2
On Fri, Jun 5, 2020 at 3:10 PM Ilija Tovilo wrote: > > Hi internals > > > I'd like to announce the match expression v2 RFC: > > https://wiki.php.net/rfc/match_expression_v2 > > Small reminder: Two weeks have passed since I announced the match v2 > RFC with little new discussion. I'll leave it open for another two > weeks and put it to a vote then if there are no objections. I will > send another reminder one day before I do. > > Ilija > > -- > PHP Internals - PHP Runtime Development Mailing List > To unsubscribe, visit: http://www.php.net/unsub.php > I really like this addition. It's a great way to decrease code verbosity without getting in the way of anything else. Much better without the blocks too, since with blocks you might as well use functions or `switch`. I see you mentioned pattern matching, but I think this can be done quite well in userland. Have you thought about including ranges, greater/less than, or some form of `in_array()` matching? As for making the `(true)` optional, even though many are in favour of it. to me that seems like something that would happen when/if the `while (true)` becomes optional. There's a million examples of the latter on github, and I think it would be odd to make this optional while (no pun intended) the `while` one would not be. Thanks, Peter
