Yes, it'll work just fine. It will even work if the outer subroutine is a lexical closure and passes the other subroutine one of the lexically-retained references it is holding, like this:

sub :: {return lc pop}
sub jonadab {
   my $lex = shift;
   @ARGV=qw(http://);
   return sub{
     my ($ical) = @_;
     my $closure = :: $lex.".".$ical."/".$/;
}}
my $foo = jonadab("PerlMonks");
$\=$foo->("Org");
print shift;
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Note: if you turn in code like that for homework, don't expect a good grade.