CLHS: Function 1+, 1-

#

Function 1+, 1-

Syntax:

1+ number => successor

1- number => predecessor

Arguments and Values:

number---a number.

successor, predecessor---a number.

Description:

1+ returns a number that is one more than its argument number. 1- returns a number that is one less than its argument number.

Examples:

     (1+ 99) =>  100
     (1- 100) =>  99
     (1+ (complex 0.0)) =>  #C(1.0 0.0)
     (1- 5/3) =>  2/3

Affected By: None.

Exceptional Situations:

Might signal type-error if its argument is not a number. Might signal arithmetic-error.

See Also:

incf, decf

Notes:

     (1+ number) ==  (+ number 1)
     (1- number) ==  (- number 1)

Implementors are encouraged to make the performance of both the previous expressions be the same.

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