freeze.js - immutable JS object helpers

freeze.js

// Shorthand for Object.freeze
export const freeze = Object.freeze

// Define an immutable model intializer.
// Objects are frozen on the way out.
export const Model = init => flags => freeze(init(flags))

// Put a value to a key, returning a new frozen object
export const put = (state, key, val) => freeze({...state, [key]: val})

// Append an array to another array.
// Returns a frozen array.
export const append = (a, b) => freeze([...a, ...b])

// Merge a patch onto a state.
// Returns a new frozen state.
export const merge = (state, patch) => freeze({...state, ...patch})