+- read side of pipe
                             /
          ----------         ----------
STDIN --> | reader | -pipe-> | writer | --> STDOUT
          ----------         ----------
                    \
                     +- write side of pipe

##</code><code>##

use strict;
use warnings;

use IO::Pipely qw(pipely);
use POE qw(Wheel::ReadWrite);

my ($read_pipe, $write_pipe) = pipely();

# reader sends output to the write pipe
my $reader = POE::Session->create(
    args => [ $write_pipe ],
    inline_states => {
        _start => sub {
            $_[HEAP]->{wheel} = POE::Wheel::ReadWrite->new(
                InputHandle  => \*STDIN,
                OutputHandle => $_[ARG0],
                InputEvent   => 'got_input',
                ErrorEvent   => 'got_input_error',
            );
        },
        got_input          => \&handle_input,
        got_input_error    => \&handle_input_error,
        process_next_input => \&process_next_input,
    }
);

# writer reads input from the read pipe
my $writer = POE::Session->create(
    args => [$read_pipe],
    inline_states => {
        _start => sub {
            $_[HEAP]->{wheel} = POE::Wheel::ReadWrite->new(
                InputHandle  => $_[ARG0],
                OutputHandle => \*STDOUT,
                InputEvent   => 'got_input',
                ErrorEvent   => 'got_input_error',
            );
        },
        got_input          => \&handle_input,
        got_input_error    => \&handle_input_error,
        process_next_input => \&process_next_input,
    }
);

POE::Kernel->run();
exit;

sub handle_input
{
    my ( $kernel, $heap, $input ) = @_[KERNEL, HEAP, ARG0];
    print $heap->{wheel}->put( $input );
    $heap->{wheel}->flush();
    $heap->{wheel}->pause_input();
    $kernel->yield( 'process_next_input' );
}

sub handle_input_error
{
    my ($kernel, $heap) = @_[KERNEL, HEAP];
    $kernel->yield( 'process_next_input' );
    delete $heap->{wheel};
}

sub process_next_input
{
    my ($kernel, $heap) = @_[KERNEL, HEAP];
    $heap->{wheel}->resume_input() if $heap->{wheel};
}

##</code><code>##

ombibulous> perl cat.pl < test.csv
00001,2,3,4
0a,b,c,d
0foo,bar,baz
^C
ombibulous>