Internal symbols in packages you have kept may still be shaken out. If any such symbol must be kept in the application, it can be retained by force in the following three ways:
This is the recommended solution. See :keep-symbols (page :keep-symbols).
External symbols are always shaken during delivery.
You can override this behavior by passing
deliver . See :shake-externals (page :shake-externals). You can also specify
:packages-to-keep-externals , pages :packages-to-keep-externals and :packages-to-shake-externals.
A reference from the object to the symbol ensures that the garbage collector passes over it during delivery.
See also Coping with INTERN and FIND-SYMBOL at runtime.