Are you replying to me (AnomalousMonk) or to the Anonymous Monk?

I tried a few variations and I can't seem to make that work.

Show your efforts :)

What do you think is wrong with it?

Can you supply a self-contained, working example?

Theoretically :) did you try Basic debugging checklist?

I think this ought to show what is wrong with my syntax

#!/usr/bin/perl --
use strict; use warnings; use Data::Dump;
my $str = "xxxx yy zzzzz xxxx qqq";
my $lengthy = sub { warn 1 };
my @list = grep $lengthy, split /\W/, $str;
dd \@list;
__END__
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Its basically as if I wrote grep 1, ...

and here I thought grep knew to take a subroutine reference, it works with grep \&somename, but it has to be grep $lengthy->(),...

And on top of that no warnings of any kind, surprising

#!/usr/bin/perl --
use strict; use warnings; use Data::Dump;
my $str = "xxxx yy zzzzz xxxx qqq sixsix";
my $lengthy = do {
   my @lengths = ( 2, 6, 6 );
   my $lix = 0;
   sub {
       warn "shabba @_ $_";
      if( $lix < @lengths and $lengths[ $lix ] == length $_ ){
          $lix++;
          return !!1;
      }
      return !!0;
   }
};
#~ grep 1, #~ my @list = grep $lengthy, split /\W/, $str;
#~ grep 1, #~ my @list = grep sub { $lengthy->() }, split /\W/, $str;
#~ slower #~ my @list = grep { $lengthy->() } split /\W/, $str;
my @list = grep $lengthy->() , split /\W/, $str;
dd \@list;
__END__
shabba  xxxx at funk line 8.
shabba  yy at funk line 8.
shabba  zzzzz at funk line 8.
shabba  xxxx at funk line 8.
shabba  qqq at funk line 8.
shabba  sixsix at funk line 8.
["yy", "sixsix"]
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