@thi.ng/atom

@thi.ng/atom

About

Clojure inspired mutable wrappers for (usually) immutable values, with support for watches.

TODO

Installation

yarn add @thi.ng/atom

Usage examples

Atom

import * as atom from "@thi.ng/atom";

const a = new atom.Atom(23);

// obtain value via deref()
a.deref();
// 23

// add watch to observe value changes
a.addWatch("foo", (id, prev, curr) => console.log(`${id}: ${prev} -> ${curr}`));
// true

a.swap((val)=> val + 1);
// foo: 23 -> 24

a.reset(42);
// foo: 24 -> 42

Cursor

// main state
main = new atom.Atom({a: 23, b: 42});

// cursor to `a` value
// requires both a lookup & update function to given value
// both fns will be called with cursor's parent state
// the updater MUST NOT mutate in place
cursor = new atom.Cursor(main, (state) => state.a, (state, x) => ({...state, a: x}));

// add watch just as with Atom
cursor.addWatch("foo", console.log);

cursor.deref()
// 23

cursor.swap(x => x + 1);
// foo 23 24

main.deref()
// { a: 24, b: 42 }

Authors

• Karsten Schmidt

License

© 2018 Karsten Schmidt // Apache Software License 2.0