nixpkgs/pkgs/development/libraries/slib/setup-hook.sh

addSlibPath () {
    if test -f "$1/lib/slib/slibcat"
    then
	export SCHEME_LIBRARY_PATH="$1/lib/slib/"
	echo "SLIB found in \`$1'; setting \$SCHEME_LIBRARY_PATH to \`$SCHEME_LIBRARY_PATH'"

	# This is needed so that `(load-from-path "slib/guile.init")' works.
	export GUILE_LOAD_PATH="$1/lib:$GUILE_LOAD_PATH"
	echo "SLIB: setting \$GUILE_LOAD_PATH to \`$GUILE_LOAD_PATH'"
    fi
}

envHooks+=(addSlibPath)