Declaration EXT:NOTSPECIAL. Declarations (PROCLAIM '(SPECIAL variable)) and DEFCONSTANT are undone by the (PROCLAIM '(EXT:NOTSPECIAL variable)) declaration. This declaration can be used only in global PROCLAIM and DECLAIM forms, not in local DECLARE forms. Of course, you cannot expect miracles: functions compiled before the EXT:NOTSPECIAL proclamation was issued will still be treating variable as special even after the EXT:NOTSPECIAL proclamation.

Function EXT:SPECIAL-VARIABLE-P. You can use the function (EXT:SPECIAL-VARIABLE-P symbol &OPTIONAL environment) to check whether the symbol is a special variable. environment of NIL or omitted means use the global environment. You can also obtain the current lexical environment using the macro EXT:THE-ENVIRONMENT (interpreted code only). This function will always return T for global special variables and constant variables.

Declaration (OPTIMIZE (SAFETY 3)) results in “safe” compiled code: function calls are never eliminated. This guarantees the semantics described in [ANSI CL] Section 3.5.

The declaration (COMPILE) has the effect that the current form is compiled prior to execution. Examples:

(LOCALLY (DECLARE (compile)) form)

executes a compiled version of form.

(LET ((x 0))
  (FLET ((inc () (DECLARE (compile)) (INCF x))
         (dec () (DECF x)))
    (VALUES #'inc #'dec)))

returns two functions. The first is compiled and increments x, the second is interpreted (slower) and decrements the same x.

The type assertion (THE value-type form) enforces a type check in interpreted code. No type check is done in compiled code. See also the EXT:ETHE macro.

The declaration determines what metadata is recorded in the function object: