The Guile-Lib package as a whole may be redistributed under the GNU
General Public License as published by the Free Software Foundation,
either version 3, or (at your option) any later version.

Each module contained in Guile-Lib has its own copying conditions,
specified in the comments at the beginning of the module's source file.

For example, src/apicheck.scm has the following header:

    ;; (apicheck) -- check for API incompatibilities
    ;; Copyright (C) 2007  Andy Wingo <wingo at pobox dot com>

    ;; 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 3 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, see <http://www.gnu.org/licenses/>.

Thus this module may be redistributed in accordance with the terms of
the GNU GPL version 3 or higher. A copy of the GPL version 3 may be
found in COPYING.GPL.

There are some modules licensed under the Lesser GPL. A copy of the
Lesser GPL version 3 may be found in COPYING.LGPL.

Other modules are in the public domain, or have restrictions on them
that are compatible with the GPLv3 (e.g. src/math/primes.scm). Please
consult the modules in question for the exact conditions.