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Date: Wed, 2 Sep 2015 23:48:09 +0100
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Subject: Re: [PHP-DEV] [RFC] [Discussion] Short Closures
From: rowan.collins@gmail.com (Rowan Collins)

On 02/09/2015 22:49, Sara Golemon wrote:
> Beautiful code is code that is easier to
> maintain, and code that is easier to maintain is often more secure and
> reliable.

I think this is an important point. Obviously, "beauty" is subjective: 
some people will find very verbose, English-like code easier to read; 
others might try to squeeze as much information into one screenful as 
possible, so they can see the whole program at a glance.

At one extreme, SQL has mandatory words like the "AS" in "CAST(x AS 
int)" just to "look more like English"; at the other, APL has symbols 
all of its own with their own Unicode code points. Most languages aim 
for some compromise in between.


So I would like to put forward for consideration these amendments to the 
proposal, in the spirit of compromise (in no particular order; numbers 
are just for reference in future discussion):

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.

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...

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".

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


Perhaps there are other thoughts along these lines that could move the 
proposal beyond a simple love/hate debate.

Regards,

-- 
Rowan Collins
[IMSoP]