The paradigms described so far give access to the REDUCE facilities at the top level. They enable a compact programming close to the application problem. No knowledge about the internal data structures is necessary, since REDUCE converts data automatically to the formats needed locally for each evaluation step. On the other hand, such frequent conversions are time consuming and so for very large problems it might be desirable to keep intermediate results in the internal form in order to avoid the conversion overhead. Here the ``symbolic'' mode of REDUCE can be used, which allows the access to internal data structures and procedures directly with the same syntax as in top level programming.
Of course, this level of programming requires some knowledge about LISP and about internal REDUCE structures. However, it enables the implementation of algorithms with the highest possible efficiency.
see also: REDUCE Home Page