optimize (ANSI and GNU Common Lisp Document)

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#### 3.8.25 optimize [Declaration]

#### Syntax::

`(optimize {quality | (quality value)}*)`

#### Arguments::

quality—an optimize quality.

value—one of the integers `0`, `1`, `2`, or `3`.

#### Valid Context::

declaration or proclamation

#### Description::

Advises the compiler that each quality should be given attention according to the specified corresponding value. Each quality must be a symbol naming an optimize quality; the names and meanings of the standard optimize qualities are shown in Figure 3–25.

      Name               Meaning
      compilation-speed  speed of the compilation process
      debug              ease of debugging
      safety             run-time error checking
      space              both code size and run-time space
      speed              speed of the object code

                 Figure 3–25: Optimize qualities

There may be other, implementation-defined optimize qualities.

A value `0` means that the corresponding quality is totally unimportant, and `3` that the quality is extremely important; `1` and `2` are intermediate values, with `1` the neutral value. `(quality 3)` can be abbreviated to quality.

Note that code which has the optimization `(safety 3)`, or just safety, is called safe code.

The consequences are unspecified if a quality appears more than once with different values.

#### Examples::

     (defun often-used-subroutine (x y)
       (declare (optimize (safety 2)))
       (error-check x y)
       (hairy-setup x)
       (do ((i 0 (+ i 1))
            (z x (cdr z)))
           ((null z))
         ;; This inner loop really needs to burn.
         (declare (optimize speed))
         (declare (fixnum i))
         ))

#### See Also::

declare, declaim , proclaim , Declaration Scope

#### Notes::

An optimize declaration never applies to either a variable or a function binding. An optimize declaration can only be a free declaration. For more information, see Declaration Scope.

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