Currying

• Currying is a transformation of functions that translates a function from callable as f(a, b, c) into callable as f(a)(b)(c)
• process of taking a function with multiple arguments and turning it into a sequence of functions each with only a single argument
• Currying doesn’t call a function. It just transforms it

function curry(f) { // curry(f) does the currying transform
  return function(a) {
    return function(b) {
      return f(a, b);
    };
  };
}
 
// usage
function sum(a, b) {
  return a + b;
}
 
let curriedSum = curry(sum); // currying transforms to another function but does not call sum function
 
alert( curriedSum(1)(2) ); // 3

Uses

• We can create partial functions using currying which are useful

// assume
function log(date, importance, message) {
  console.log(`[${date.getHours()}:${date.getMinutes()} [${importance}] ${message}`);
}
 
log = _.curry(log); // using lodash curry function
 
// Now log is available in both the following forms:
log(new Date(), "DEBUG", "some debug");
log(new Date())("DEBUG")("some debug");
 
 
 
// In the beginning we will create logNow which will be the partial of log with fixed first argument
let logNow = log(new Date());
 
// Now we will use it in the cod
logNow("INFO", "message"); // [HH:mm] INFO message

Is it possible to curry function generically???

• lodash provide generic curry function??