PERLDB_OPTS="ReadLine=0" MASTER_TTY=`tty` xterm -e perl -d calc_TRL.pl

with

use Term::ReadLine;
my $tty=$ENV{MASTER_TTY};

open my $out,'>',$tty;
open my $in,'<',$tty;


my $term = Term::ReadLine->new('Simple Perl calc',$in,$out);
my $prompt = "Enter code: ";
my $OUT = $term->OUT || \*STDOUT;
while ( $_ = $term->readline($prompt) ) {
  my $res = eval($_);
  warn $@ if $@;
  print $OUT $res, "\n" unless $@;
  $term->addhistory($_) if /\S/;
}
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otherwise the debugger starts spontaneously to write to the master terminal, IMHO a bug somewhere between debugger and TRL.

My former approach to redirect the app's tty to a slave terminal has the advantage to run without lost of features in IDEs like emacs.

The slave terminal can also be an extra sub-window within the IDE running a terminal emulation.