How to subtract an array from an array?
When I try the following

    #!/usr/bin/perl
    
    use strict;
    use warnings;
    use Data::Dumper;
    
    my @bl = qw(red green blue);
    my @a = qw(green yellow purple blue pink);
    
    print Dumper [grep {not @bl} @a];

I get an empty array. I would have expected that `@bl` was subtracted from `@a`, so the output was `yellow purple pink`.

What's wrong here?

How to subtract an array from an array?
===

When I try the following

    #!/usr/bin/perl
    
    use strict;
    use warnings;
    use Data::Dumper;
    
    my @bl = qw(red green blue);
    my @a = qw(green yellow purple blue pink);
    
    print Dumper [grep {not @bl} @a];

I get an empty array. I would have expected that `@bl` was subtracted from `@a`, so the output was `yellow purple pink`.

What's wrong here?
