lisp 전역변수 / 지역변수

define a parameter

(defparameter <sym> <val> [<comment>])

fsubr.

<sym> the symbol (will be marked special)

<val> the value

<comment>  optional comment string (ignored)

returns the value

define a variable

(defvar <sym> [<val> [<comment>]])

fsubr.  Variable only initialized if not previously defined.

<sym> the symbol (will be marked special)

<val> the initial value, or NIL if absent.

<comment>  optional comment string (ignored)

returns the current value

set the global value of a symbol

(set <sym> <expr>)

You can also use (setf (symbol-value <sym>) <expr>)

<sym> the symbol being set

<expr> the new value

returns the new value

set the value of a symbol

(setq [<sym> <expr>]...)

fsubr. You can also use (setf <sym> <expr>)

<sym> the symbol being set (quoted)

<expr> the new value

returns the last new value or NIL if no arguments

전역변수
(defparameter *var_name* value) 마지막에 정의된것으로 변경가능
(defvar *var_name* value) 처음 정의된것으로 고정

> (defparameter *a* 1) *a* > *a* 1 > (defparameter *a* 2) *a* > *a* 2

> (defvar*a* 1) *a* > *a* 1> (defvar *a* 2) *a* > *a* 1

지역변수
(let ((variable_declarations)) (body)

> (let ((*a* 5)) (princ *a*)) 5 5 > *a* 1