#!/usr/bin/perl

use strict;
use warnings;

use Data::Dump 'pp';
use Data::Dumper;

my $file_name = "file.csv";

open my $lines, '<', $file_name
  or die "Can't open file $file_name, $!";

my @parms = qw( date day name );

while (my $line = <$lines>) {

    next unless $line =~ /\S/;  # <- add

   chomp $line;
   
   my $data;

   
   ( $data->{ date }, $data->{ day }, $data->{ name } ) = split(/,/, $
+line);
   
   pp @{ $data }{ (@parms) };
}
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What do you get with this

#!/usr/bin/perl
use strict;
use warnings;
use Data::Dump 'pp';

my $file_name = "file.csv";
open my $lines, '<', $file_name
  or die "Can't open file $file_name, $!";

while (my $line = <$lines>) {
  pp $line;
}
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It prints all the data from the file no problem, this line also prints:

print "$data->{ date }, $data->{ day }, $data->{ name }\n"
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This one gets me nothing:

 pp @{ $data }{ (@parms) };
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My Perl version is current, I get undef for all values.

Here's what I get from the code you just posted and the data from above:

c:\@Work\Perl\monks\Anonymous Monk\1158543>perl -e
"use strict;
 use warnings;
 ;;
 use Data::Dump 'pp';
 use Data::Dumper;
 ;;
 my $file_name = \"file.csv\";
 ;;
 open my $lines, '<', $file_name
   or die \"Can't open file $file_name, $!\";
 ;;
 my @parms = qw( date day name );
 ;;
 while (my $line = <$lines>) {
   next unless $line =~ /\S/;
   chomp $line;
   my $data;
   ( $data->{ date }, $data->{ day }, $data->{ name } ) = split(/,/, $
+line);
   pp @{ $data }{ (@parms) };
  }
"
("01/04/2014", "Friday", "Joe")
("02/11/2011", "Monday", "Mary")
("05/09/2016", "Monday", "Ann")
("07/02/2013", "MOnday", "Marc")
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---

Give a man a fish:  <%-{-{-{-<

It's a mystery to me, why this line:

print "$data->{ date }, $data->{ day }, $data->{ name }\n"
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prints all the values and this one gets me undefs:

 pp @{ $data }{ (@parms) };
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I'm stuck on this one!

And this line prints anything for you?

pp @{ $data }{ (@parms) };
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