Ohhhhhh. I see. Thank you for pointing that out! I've avoided using Prototypes in my own code, and had almost forgotten about them.

FWIW, I much prefer the more explicit syntax that you gave as an equivalent example. That is, something like this seems sensible and obvious to me:

#!/usr/bin/env perl

use strict;
use warnings;

sub call_it {
    my $fn_ref = shift;
    &{$fn_ref}();
}

call_it( sub { print "hi\n"  } );
call_it( sub { print "bye\n" } );
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