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incf


Type:   -   Lisp macro (closure)
Source:   -   misc.lsp

Syntax

(incf symbol)
symbol - a symbol with numerical value bound to it
returns - the new value of the symbol

In Nyquist, 'incf' is implemented as a Lisp macro:

(defmacro incf (symbol)
  `(setf ,symbol (1+ ,symbol)))

Description

The 'incf' macro is used for incrementing a numerical value of a variable. 1 is added to the number and the result is stored in the variable. An error is signalled if the variable doesn't hold a number.

Examples

(setq n 1)     => 1
(incf n)       => 2
n              => 2
(incf n)       => 3

(setq n -1.8)  => -1.8
(incf n)       => -0.8
(incf n)       => 0.2
(incf n)       => 1.2
n              => 1.2

(setq n #\a)  => #\a
(incf a)      => error: bad argument type - #\a

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Nyquist / XLISP 2.0  -  Contents | Tutorials | Examples | Reference