I don't know if smart match can do this, but you could consider List::MoreUtils:

use warnings;
use strict;
use List::MoreUtils qw(firstidx);

my @list = (1, 4, 3, 2, 4, 6);
printf "item with index %i in list is 4\n", firstidx { $_ == 4 } @list
+;

__END__

item with index 1 in list is 4
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