I don't think they deserve to be added to the core. They might be a good addition to List::Util, though. Actually the one you call add() already is there. It's called sum() ;-)

use List::Util qw(reduce);

sub reduce_c (&) { my $block = shift(); return sub {&reduce($block, @_
+)}}

my $plus = reduce_c {$a+$b};
print $plus->(1,2,3,4,5), "\n";

*tajms = reduce_c {$a*$b};
print tajms(1,2,3,4,5), "\n";
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