xen-orchestra/@vates/predicates/.USAGE.md

`undefined` predicates are ignored and `undefined` is returned if all predicates are `undefined`, this permits the most efficient composition:

```js
const compositePredicate = not(every(undefined, some(not(predicate2), undefined)))

// ends up as

const compositePredicate = predicate2
```

Predicates can also be passed wrapped in an array:

```js
const compositePredicate = every([predicate1, some([predicate2, predicate3])])
```

`this` and all arguments are passed to the nested predicates.

### `every(predicates)`

> Returns a predicate that returns `true` iff every predicate returns `true`.

```js
const isBetween3And7 = every(
  n => n >= 3,
  n => n <= 7
)

isBetween3And10(0)
// → false

isBetween3And10(5)
// → true

isBetween3And10(10)
// → false
```

### `not(predicate)`

> Returns a predicate that returns the negation of the predicate.

```js
const isEven = n => n % 2 === 0
const isOdd = not(isEven)

isOdd(1)
// true

isOdd(2)
// false
```

### `some(predicates)`

> Returns a predicate that returns `true` iff some predicate returns `true`.

```js
const isAliceOrBob = some(
  name => name === 'Alice',
  name => name === 'Bob'
)

isAliceOrBob('Alice')
// → true

isAliceOrBob('Bob')
// → true

isAliceOrBob('Oscar')
// → false
```