This is the Debian package unlambda.

It was Debianised by Andrew Stribblehill on 2002-05-29
from http://www.eleves.ens.fr:8080/home/madore/programs/unlambda/

The binary file, /usr/bin/unlambda, is licensed under the GNU GPL:

/* Copyright (C) 1999 by David A. Madore <david.madore@ens.fr> */

/* This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty
 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
 * the GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */

On Debian GNU/Linux systems, the complete text of the GNU General
Public License can be found in `/usr/share/common-licenses/GPL'.