the symbol, prohibits both lexical and dynamic binding. This is mainly an
efficiency measure for threaded platforms, but also valueable in
expressing intent.
+ * optimization: the compiler uses a specialized version of FILL when the
+ element type is know in more cases, making eg. (UNSIGNED-BYTE 8) case
+ almost 90% faster.
* optimization: accesses to potentially non-simple arrays where element type
is known are 50% faster.
* optimization: compiler now generates faster array typechecking code.