* guix/scripts/archive.scm, tests/guix-archive.sh: New files. * Makefile.am (MODULES): Add 'archive.scm'. (SH_TESTS): Add 'guix-archive.sh'. * doc/guix.texi (Invoking guix archive): New section. * guix/scripts/build.scm: Export 'derivation-from-expression'. * guix/scripts/package.scm: Export 'specification->package+output'.