Persistent

Persistent data-structures from the comfort of JavaScript - a lá clojure.

Why?

Mutability causes headaches; immutability soothes them. JavaScript's Object and Array are crying out for immutable counterparts to complement first-class functions.

Example

``javascript
var p = require('persistent'),
person = p.dict({ firstName: 'hugh', secondName: 'jackson' })

var personWithAge = person.set({ age: 24 })

person.has('age') //= false
personWithAge.has('age') //= true
personWithAge.get('age') //= true
`

Install

npm install persistent

persistent.dict([Object]) -> dict

Creates an empty dict, or sets the attributes if an object is passed.

`javascript
var o = p.dict()

// or
var you = p.dict({ wise: true, willUseThisLib: true })
`

$3

Returns a new dict with the additional attribute(s).

`javascript
var o = p.dict()

var changed = o.set('x', 3).set({ y: 4, z: 5 })

changed.has('x') //= true
changed.get('y') //= 4
`

$3

Gets an attribute.

`
var o = p.dict({ x: 3, y: 4 })

o.get('x') //= 3
`

$3

Returns true or false; same as key in object for regular objects:

`
var o = p.dict({ x: 3, y: 4 })

o.has('x') //= true
o.has('z') //= false
`

$3

Returns a new dict with the key removed.

`
var o = p.dict({
foo: 'bar',
baz: 'quux'
})

var updated = o.remove('foo').remove('baz')
updated.has('foo') //= false
o.has('foo') //= true
`

$3

Returns a seperate, mutable object with the same attrs.

`
var o = p.dict({
foo: 'bar',
baz: 'quux'
})

var trans = o.transient()
delete trans.foo

o.has('foo') //= true
``