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Date: Thu, 3 Sep 2015 16:42:11 -0700
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To: Rowan Collins <rowan.collins@gmail.com>
Cc: PHP internals <internals@lists.php.net>
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Subject: Re: [PHP-DEV] [RFC] [Discussion] Short Closures
From: pollita@php.net (Sara Golemon)

On Wed, Sep 2, 2015 at 3:48 PM, Rowan Collins <rowan.collins@gmail.com> wrote:
> Amendment 1. Only allow the single-expression form of the short syntax; full
> function bodies must be declared with the existing function(){ ... } syntax.
> This gives a clearer distinction between how the two syntaxes can be used.
>
I'm down with that.  Short syntax works best when it's concise.  If my
callback needs to do more, I tend to prefer writing the method
elsewhere, and naming the variable its in according to what it does.
Yay readability!

> Amendment 2. Make the ~> operator non-associative, so that lambdas returning
> lambdas would need an extra pair of brackets making the nesting explicit. To
> take one of Anthony's examples:
>
> function partial(callable $cb) {
>     return $left ~> ( $right ~> $cb($left, $right) );
> }
>
> It's now at least clearer that there are two different anonymous functions
> here, even if it's not entirely clear what they're trying to achieve...
>
Again, I support this.  I use parenthesis generously so that there's
never a doubt.  And because we got ternary's associativity wrong.

> Amendment 3. Make the parentheses around the argument list mandatory so that
> (if Amendment 1 is also adopted) there is only a single variant of the
> syntax, namely "( param list ) ~> expression".
>
I like it for consistency, but I will say that 80% of my short lambda
uses are callbacks for map and filter, which are single arg callbacks
(when used without keys), so I do seldom see parens used at all.... in
fact, I think that just convinced me why we need to be consistent.
Imagine someone not understanding why adding a second parameter breaks
their short lamba declaration...

> Amendment 4. Consider a syntax involving an explicit "use". This one
> requires a bit more exploration, but maybe something like:
> ( $a use $b ) ~> $a + $b
> or:
> ( $a ) use ( $b ) ~> $a + $b
>
Not a fan of this one at all.  Maybe it's my Javascript showing
through, but I like the automatic capture.  Not that I'd cry foul if
it were required though.  Good short lambdas are short short lambdas,
so their use statements would be small anyway.

-Sara