perl 'require' in begin block
===

I have the following code:

    #!/usr/bin/env perl
    use strict;
    use warnings;
    use feature 'say';
    
    BEGIN {
           my $supported = undef;
           *compute_factorial = sub { if (eval { require bignum; bignum->import(); 1;}) {
                                        my $num       = shift;
                                        my $factorial = 1;
                                        foreach my $num (1..$num) {
                                            $factorial *= $num; 
                                        }
                                        return $factorial;
                                      }  else {
                                           undef;
                                         } };
           };
    
    my $f = compute_factorial(25);
    say $f;


I'm just testing something, not really a production code...
I do have `bignum` pragma on my machine (perfectly loadable using `use`), I was wondering why `require` doesn't load it in this case?

Thanks,
