Of course you could take advantage of one of the few times you would actually want to use a prototype and allow a more streamlined syntax:

sub checkForDirectory (&) {
  my $cond = shift;

  ## ...
}

## ...
my $result = checkForDirectory { ! -d $_[0] };
my $also_result = checkForDirectory sub { -M $_[0] > 2 }
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Although doing it this way means that if your coderefs aren't inline (say they're coming from an array or hash based on some other external condition) you'll need to use a leading & to override the prototype check . . .

my $predicate = sub { $_[0] =~ /^\d{4}-\d{2}-\d{2}/ };
my $other_result = &checkForDirectory( $predicate );
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