Real Life Example

To understand the benefits we need a worthy real-life example.

For instance, we have the logging that formats and outputs the information. In real projects such functions have many useful features like sending logs over the network, here we’ll just use alert:

function log(date, importance, message) {
  alert(`[${date.getHours()}:${date.getMinutes()}] [${importance}] ${message}`);
}

Let’s curry it!

function log(date) {
            return (importance) => {
                return (message) => {
                    alert(`[${date.getHours()}:${date.getMinutes()}] [${importance}] ${message}`);
                }
            }
        }

Now we can easily make a convenience function for current logs

// logNow will be the partial of log with fixed first argument
let logNow = log(new Date());

// use it
logNow("INFO", "message"); // [HH:mm] INFO message

let debugNow = logNow("DEBUG");

debugNow("message"); // [HH:mm] DEBUG message