fp-and-or


Simple and and or functional programming predicates.

- and(...fs): (...args): boolean - Returns a predicate that returns true if all arguments are true or evaluate to true for the given input.
- or(...fs): (...args): boolean - Returns a predicate that returns true if at least one argument is true or evaluates to true for the given input.

A predicate is a function that returns a boolean, commonly used in Array.prototype.filter.

e.g.

``js
const isEven = n => n%2 === 0
const isPositive = n => n > 0

// un-fancy
items.filter(x => isEven(x) || isPositive(x))

// fancy
items.filter(or(isEven, isPositive))
`

Install

`sh
npm install --save fp-and-or
`

Usage

`js
const { and, or } = require('fp-and-or')

const isEven = n => n % 2 === 0
const isPositive = n => n > 0
const isBig = n => Math.abs(n) >= 1000
`

$3

#### return true with no predicates
`js
and()(1) // true
`

#### return result of single predicate
`js
and(isEven)(1) // false
and(isEven)(2) // true
`

#### return logical AND of two predicates
`js
and(isEven, isPositive)(-2) // false
and(isEven, isPositive)(-1) // false
and(isEven, isPositive)(1) // false
and(isEven, isPositive)(2) // true
`

#### return logical AND of three predicates
`js
and(isEven, isPositive, isBig)(-2) // false
and(isEven, isPositive, isBig)(-1) // false
and(isEven, isPositive, isBig)(1) // false
and(isEven, isPositive, isBig)(2) // false
and(isEven, isPositive, isBig)(-1002) // false
and(isEven, isPositive, isBig)(-1001) // false
and(isEven, isPositive, isBig)(1001) // false
and(isEven, isPositive, isBig)(1002) // true
`

#### return value of single boolean
`js
and(true)(1) // true
and(false)(1) // false
`

#### return value of two booleans
`js
and(false, false)(1) // false
and(false, true)(1) // false
and(true, false)(1) // false
and(true, true)(1) // true
`

#### return value of multiple booleans
`js
and(false, false, false)(1) // false
and(false, true, false)(1) // false
and(true, false, false)(1) // false
and(true, true, false)(1) // false
and(false, false, true)(1) // false
and(false, true, true)(1) // false
and(true, false, true)(1) // false
and(true, true, true)(1) // true
`

#### return value of mixed booleans and functions
`js
and(false, isEven)(1) // false
and(false, isEven)(2) // false
and(true, isEven)(1) // false
and(true, isEven)(2) // true
and(isEven, false)(1) // false
and(isEven, false)(2) // false
and(isEven, true)(1) // false
and(isEven, true)(2) // true
`

$3

#### return false with no predicates
`js
or()(1) // false
`

#### return result of single predicate
`js
or(isEven)(1) // false
or(isEven)(2) // true
`

#### return logical OR of two predicates
`js
or(isEven, isPositive)(-2) // true
or(isEven, isPositive)(-1) // false
or(isEven, isPositive)(1) // true
or(isEven, isPositive)(2) // true
`

#### return logical OR of three predicates
`js
or(isEven, isPositive, isBig)(-2) // true
or(isEven, isPositive, isBig)(-1) // false
or(isEven, isPositive, isBig)(0) // true
or(isEven, isPositive, isBig)(1) // true
or(isEven, isPositive, isBig)(2) // true
or(isEven, isPositive, isBig)(-1002) // true
or(isEven, isPositive, isBig)(-1001) // true
or(isEven, isPositive, isBig)(1001) // true
or(isEven, isPositive, isBig)(1002) // true
`

#### return value of single boolean
`js
or(true)(1) // true
or(false)(1) // false
`

#### return value of two booleans
`js
or(false, false)(1) // false
or(false, true)(1) // true
or(true, false)(1) // true
or(true, true)(1) // true
`

#### return value of multiple booleans
`js
or(false, false, false)(1) // false
or(false, true, false)(1) // true
or(true, false, false)(1) // true
or(true, true, false)(1) // true
or(false, false, true)(1) // true
or(false, true, true)(1) // true
or(true, false, true)(1) // true
or(true, true, true)(1) // true
`

#### return value of mixed booleans and functions
`js
or(false, isEven)(1) // false
or(false, isEven)(2) // true
or(true, isEven)(1) // true
or(true, isEven)(2) // true
or(isEven, false)(1) // false
or(isEven, false)(2) // true
or(isEven, true)(1) // true
or(isEven, true)(2) // true
``