Sure, but then you're left with

push @soln, $val if ( $soln[-1] ne $val );
[download]

and with the comma suggesting do this thing, then do that other thing, it could read like this:

push @soln                      # and then ..
$val if ( $soln[-1] ne $val );
[download]

Huh. That can't be right.

You could also use indentation to make it clearer ..

push @soln, $val
    if ( $soln[-1] ne $val );
[download]

Anyway, it's a matter of taste, and my preferences comes from writing C in the 80's.