Unlike declare, proclaim is a function that parses the declarations in the list (usually a quoted list), and puts their semantics and advice into global effect. This can be useful when compiling a file for speedy execution, since a proclamation such as:
(proclaim '(optimize (speed 3) (space 0) (debug 0)))
means the rest of the file is compiled with these optimization levels in effect. Other ways of doing this are:
:optimize option in defsystem to establish default optimization qualities for every member of the system, when compiled via compile-system.As proclaim involves parsing a list of lists of symbols and is intended to be used a few times per file at most, its implementation is not optimized for speed - it makes little sense to use it other than at top level.
Note:
For a top-level call to proclaim or declaim, optimize declarations are omitted from the compiled binary file. This deviates from the ANSI Common Lisp Standard but is useful because you are unlikely to want to change settings outside of that file. To make the global settings, you can call a function which calls proclaim (so it is not a top-level call).
See Compiler control for a more extended description of the compiler optimize qualities.
(proclaim '(special *fred*))
(proclaim '(type single-float x y z))
(proclaim '(optimize (safety 0) (speed 3)))
As proclaim involves parsing a list of lists of symbols and is intended to be used a few times per file, its implementation is not optimized for speed -- it makes little sense to use it other than at top level.
Remember to quote the argument list if it is a constant list. (proclaim (special x)) attempts to call function special.
Exercise caution if you declare or proclaim variables to be special without regard to the naming convention that surrounds their names with asterisks.
LispWorks User Guide and Reference Manual - 20 Sep 2017