Re^6: Burned by precedence rules (== true)

[TimToady]

in reply to Re^5: Burned by precedence rules (== true)
in thread Burned by precedence rules

In Perl 6 we can use positive boolean context, which helps readability a little:

if ?$x == ?$y {...}
if ?$x != ?$y {...}

We can use junctions, which again helps the different case more than the same case:

if not $x ^ $y {...}
if $x ^ $y {...}

or if you prefer:

if !one($x,$y) {...}
if one($x,$y) {...}

That's probably enough ways to do it...

[tye]

Nah. Clearly this demonstrates the utility of a few "Boolean comparison" operators:

    if $isFree ?= $isEasy
    if $isOne !?= $isOther

        unlink $dev
    eqv unlink $prod
    or  die "Inconsistent state";

         system $verifyUser
    neqv system $verifyAdmin
    or   die "You are not just either a User or an Admin";

;)

[TimToady]

Well, we can't use eqv because we already use that for something else, but we do have a Boolean not-equal already:

    $x ?^ $y

What we don't have is a Boolean equal. I thought about adding:

    $x ?= $y

but people would probably think that means:

    $x = $x ? $y;

which is nonsense, but they'd still think it. :-)

Anyway, the utility is not worth the extra complexity, in my opinion. Comparing two Booleans for equivalence is an odd enough thing to do that I don't mind if it looks a little odd.

[tye]

Note that I did include a winky smiley. But I saved the clincher argument for now: Perl 6 is becoming so like VB, it will be very surprising to VBers when the purpose of eqv is so different. :-D

[tilly]

What about saying that !( potential boolean operator ) means the boolean negation of the boolean operator? That would naturally give you the logical operators !&& (nand), !|| (nor) and !^ (not xor). The last would, of course, be Boolean equals.

(I can't believe I just suggested that.)