none() Function

Function

none( predicate, list, context )

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.

Parameters

Keyword Type Description

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

Usage considerations

Referencing expressions and rules

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

Understanding results

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

Empty and null lists yield true.

Limitations and alternatives

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

a!forEach() cannot be used within rules used in this function.

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

Open in Github Built: Fri, Dec 03, 2021 (02:38:50 PM)

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