if it is really easily evealuated it wll be cute, i didn't thought it will work that way :")
That way it will be possible to say :

$x := $y + 5;
...code...
$x := $z + 12 if cond1;
...code...
$x := 6 + $p if cond2;
...code...
print $x
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Now think if both cond1 and cond2 succeed ... in a normal assigment u will calculate $x three times.(what if the calculation is very complex).
In our case it will be calculated only when we call 'print'..
On the other hand using several subs for this thing is waste, not to mention that the call to sub is slow... So if I'm right := is/can-be-used-as :

1. binding
2. alaising
3. simple-sub (mostly for expressions)
4. assignment
any other ideas.. :")

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raptor