0:14 >perl -wE "@a = (1,2,3,undef,5); say scalar @a; @b = map(defined, @a); print join(',', @b);"
5
1,1,1,,1
 0:14 >perl -wE "@a = (1,2,3,undef,5); say scalar @a; @b = grep(defined, @a); print join(',', @b);"
5
1,2,3,5
 0:14 >