C:\test\primes>perl -Mstrict -MList::Util=reduce,$a,$b -wE" say reduce{ $a +$b } 1,2,3" 6 C:\test\primes>perl -Mstrict -wE"package fred; use List::Util qw[ reduce $a $b ]; say reduce{ $a +$b } 1,2,3" 6