none() Function

Calls a rule or function that returns either true or false for each item in list by asking the question, "Do all items in this list yield false for this rule/function?" with the intent to discover if no items will yield true.

Syntax

none( predicate, list, [context, … ] )

predicate: (Function, Rule, or Data Type Constructor) Expression that returns a Boolean (true or false).

list: (Any Type Array) List of elements that the predicate iterates through.

context: (Any Type Array) Variable number of parameters passed directly into each predicate evaluation.

Returns

Boolean

Notes

Use fn!functionName to reference an expression function and rule!ruleName to reference a rule.

Returns false as soon as the returned value of an evaluation yields true; otherwise, returns true.

Empty and null lists yield true.

Serves as an alternative to not(or(apply(rule!iseven, {1, 2, 3}))) and not(any(rule!iseven, {-1,0,1,2})).

Examples

You can experiment with this function in the test box below.

Test Input

Given a function f(x), none(fn!f, {a, b, c}, v) returns not(or({f(a, v), f(b, v), f(c, v)}))

none(rule!iseven,{-1,0,1,2}) returns false

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