OTOH, consider (ta-daaa) Lexical Subroutines: 

Win8 Strawberry 5.30.3.1 (64)  Wed 09/21/2022  1:32:21
C:\@Work\Perl\monks
>perl

use 5.018;  # lexical subroutines

use strict;
use warnings;

Outer(1);
# Inner(2);  # Undefined subroutine &main::Inner ...

sub Outer {

    my ($param) = @_;

    my sub Inner {
        my ($innerVar) = @_;
        print "In inner: $innerVar\n";
        }

    Inner($param);

    }

^Z
In inner: 1

[download]
I haven't used lexical subs very much myself, so I can't offer advice about possible pitfalls. And closures are always a bit tricky. If you really want to have fun with closures, see Dominus's Higher-Order Perl (free download).

Update: And the second of GrandFather's examples: 

Win8 Strawberry 5.30.3.1 (64)  Wed 09/21/2022  1:46:46
C:\@Work\Perl\monks
>perl

use 5.018;  # lexical subs

use strict;
use warnings;

Outer(1);
# Inner();  # still not there
Outer(1);

sub Outer {

    my ($param) = @_;

    my sub Inner {
        print "In inner: $param\n";
        ++$param;
        }

    Inner();

    }

^Z
In inner: 1
In inner: 1

[download]

Give a man a fish:  <%-{-{-{-<

In reply to Re: Recursive subroutines and closures (updated) by AnomalousMonk
in thread Recursive subroutines and closures by ibm1620

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