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lispelispcommon-lisp

How to delete variable/forms in Lisp?

In Python we have the del statement for deleting variables.

E.g: 

a = 1
del a

What the equivalent of this in Lisp?

(setq foo 1)
;; (del foo) ?
Solution

  • In Common Lisp.

    For symbols as variables:

    CL-USER 7 > (setf foo 42)
42

CL-USER 8 > foo
42

CL-USER 9 > (makunbound 'foo)
FOO

CL-USER 10 > foo

Error: The variable FOO is unbound.

    See:

    • MAKUNBOUND (defined)
    • SLOT-MAKUNBOUND (defined)
    • FMAKUNBOUND (defined)