use v5.12;
use warnings;
use Data::Dump qw/pp dd/;


my $X =
  [
   [1, -4, 7],
   [-2, 3, 3]
  ];

my $Y =
  [
   [8, -9, -6,  5],
   [1, -3, -4,  7],
   [2,  8, -8, -3],
   [1,  2, -5, -1]
  ];

pp $X;
pp $Y;

my $X_Y =
  [
   map {
       my $x = $_;
       map {
           my $y = $_;
           [
            map {
                my $xx = $_;
                map { $xx * $_ } @$y
            } @$x
           ]
       } @$Y
   } @$X
  ];

pp $X_Y;