CREATE OR REPLACE FUNCTION recurse_plperl(i int) RETURNS SETOF TEXT LANGUAGE plperl
AS $$
	my $i = shift;
	my $res = [];
	return $res unless $i > 0;
	push @$res, "plperl  $i entry: ".((eval "stat;1") ? "ok" : $@);
	push @$res, $_
		for map { $_->{recurse_plperlu} }
			@{spi_exec_query("select * from recurse_plperlu($i-1)")->{rows}};
	return $res;
$$;
CREATE OR REPLACE FUNCTION recurse_plperlu(i int) RETURNS SETOF TEXT LANGUAGE plperlu
AS $$
	my $i = shift;
        my $res = [];
        return $res unless $i > 0;
	push @$res, "plperlu $i entry: ".((eval "stat;1") ? "ok" : $@);
	push @$res, $_
		for map { $_->{recurse_plperl} }
			@{spi_exec_query("select * from recurse_plperl($i-1)")->{rows}};
	return $res;
$$;
SELECT * FROM recurse_plperl(5);
                             recurse_plperl                             
------------------------------------------------------------------------
 plperl  5 entry: 'stat' trapped by operation mask at (eval 4) line 1.

 plperlu 4 entry: ok
 plperl  3 entry: 'stat' trapped by operation mask at (eval 5) line 1.

 plperlu 2 entry: ok
 plperl  1 entry: 'stat' trapped by operation mask at (eval 6) line 1.

(5 rows)

SELECT * FROM recurse_plperlu(5);
                            recurse_plperlu                             
------------------------------------------------------------------------
 plperlu 5 entry: ok
 plperl  4 entry: 'stat' trapped by operation mask at (eval 7) line 1.

 plperlu 3 entry: ok
 plperl  2 entry: 'stat' trapped by operation mask at (eval 8) line 1.

 plperlu 1 entry: ok
(5 rows)

CREATE OR REPLACE FUNCTION use_plperlu() RETURNS void LANGUAGE plperlu
AS $$
use Errno;
$$;
CREATE OR REPLACE FUNCTION use_plperl() RETURNS void LANGUAGE plperl
AS $$
use Errno;
$$;
select use_plperl();
ERROR:  creation of Perl function failed: Unable to load Errno.pm into plperl at (eval 9) line 2.
BEGIN failed--compilation aborted at (eval 9) line 2.
select use_plperlu();
 use_plperlu 
-------------
 
(1 row)

CREATE OR REPLACE FUNCTION use_plperl() RETURNS void LANGUAGE plperl
AS $$
use Errno;
$$;
select use_plperl();
ERROR:  creation of Perl function failed: Unable to load Errno.pm into plperl at (eval 10) line 2.
BEGIN failed--compilation aborted at (eval 10) line 2.