ANSI Common Lisp   3 Evaluation and Compilation

3.3 Declarations

Declarations provide a way of specifying information for use by program processors, such as the evaluator or the compiler.

Local declarations can be embedded in executable code using declare. Global declarations, or proclamations, are established by proclaim or declaim.

The the special form provides a shorthand notation for making a local declaration about the type of the value of a given form.

The consequences are undefined if a program violates a declaration or a proclamation.

3.3.1  Minimal Declaration Processing Requirements
3.3.2  Declaration Specifiers
3.3.3  Declaration Identifiers
3.3.4  Declaration Scope