gistfile1.pl

use v5.14;
use strict;
use warnings;

use utf8;
use Encode qw( decode encode is_utf8 );

my $bytes = join q{}, map { chr($_) } 240, 159, 152, 184;
say $bytes;

my $unicode = decode( 'utf-8', $bytes );

my $maybe_utf8 = "$bytes $unicode";
say is_utf8($maybe_utf8) ? 'yes' : 'no';