`=.`

[foremtehan]

Description

I was wondering, why don’t we have an operator that performs the opposite of the concatenating assignment operator .=? This new operator could prepend a value:

$a = " World";
$a =. "Hello"; // Result: "Hello World!"

What's the problem with this?

[nielsdos]

This won't generalise well.
The reason .= exists is because all other binary operators can be used in compound form as well, e.g. +=, -=, ... so it makes sense to have .= too.
However, =+ and =- would be ambiguous, consider this: $a =- 3. Does this means "set $a to -3" or "subtract 3 from $a".
It would be inconsistent to have =. as an exception.

[thg2k]

I usually dislike syntactic sugar, but I have to say it happens quite often to write $var = "something" . $var; and most of the other operators are symmetric so.. it might make sense to have that exception.

[nielsdos]

It would most definitely require an RFC.
It also just occurred to me that =. is already ambiguous with decimal numbers.