To clarify @$c[0] means the same as @{$c}[0] meaning dereference $c, take array slice
Well... I'm not sure it's that much more clear. After all, "I know what I mean, ..."
I'm still puzzled by the absence of a "... better written as ..." warning. Maybe the usage is just too far off the beaten track for warnings to stumble over.
>perl -wMstrict -le
"my @c = ('foo');
print @c[0];
;;
my $c = ['bar'];
print @{$c}[0];
print @ $c [0];
"
Scalar value @c[0] better written as $c[0] at -e line 1.
foo
bar
bar