Cascade

A tiny cascading state machine.

quick-start

installation:

npm i --save @jdw/cascade

usage:

import cascade from '@jdw/cascade';

const increment = x => x++;
const square = x => Math.pow(x, x);

// apply state to functions and sequentially
// calculate a result
cascade(100)
    .chain(square)
    .chain(increment)
    .read(); // 10001

API

cascade(initialState) => Cascade

This initialization method takes an initial state and returns a Cascade object.

Cascade

chain(fn) => Cascade

This method takes function fn invoking it with the machines state as an argument and then mutating state to the result.

example:

return cascade(1)
    .chain(x => x + 1) // internal state set to: 2
    .chain(x => x * x) // internal state set to: 4
    .read()            // return internal state: 4

chain(fn, cb) => Cascade

As above however with the optional recovery method cb supplied. cb is invoked in case something went wrong with the error, state, and fn supplied as its arguments.

example:

const process = state => throw new Error();
const recover = (err, state, fn) => state + 10;

return cascade(90)
    .chain(process, recover) // errors on process() invoking recover().
    .read();                 // outputs: 100

read() => any

Returns the current state of the machine.

example:

return cascade(true)
    .read(); // true