Raganwald's example from http://raganwald.com/2018/02/23/forde.html

raganwald.fsl

machine_name: "Raganwald's example";

machine_source: http://raganwald.com/2018/02/23/forde.html ;

start_states: open;
initial_data: { balance: 0 };

open 'deposit'  { onfollow: `${(action, data) => ((data.balance += action.amount), data)}`; } -> open;
open 'withdraw' { onfollow: `${(action, data) => ((data.balance -= action.amount), data)}`; } -> open;

open 'place_hold' -> hold 'remove_hold' -> open;

[open hold] 'close' { onfollow: `${...}`; } -> closed;

close 'reopen' -> open;