Function LENGTH

• Defined in theory: Kif-lists
• Source code: kif-lists.lisp

Slots on this function:

Documentation:

The function constant {tt length} gives the number of items in a list.

Instance-Of: Function

Arity: 2

Domain: List

Range: Nonnegative-integer

Other Related Axioms:

(= (Length ?List) 0)

(<=> (Null ?List) (And (List ?List) (= (Length ?List) 0)))

(= (Length ?List) 1)

(<=> (Single ?List) (And (List ?List) (= (Length ?List) 1)))

(= (Length ?List) 2)

(<=> (Double ?List) (And (List ?List) (= (Length ?List) 2)))

(= (Length ?List) 3)

(<=> (Triple ?List) (And (List ?List) (= (Length ?List) 3)))

(<- (Length ?List)
    (Cond ((Null ?List) 0) ((List ?List) (1+ (Length (Rest ?List))))))

(=> (Length $X $Y) (Nonnegative-Integer $Y))

(=> (Length $X $Y) (List $X))