dyn-curry

What? Yet another currying module?

Yes, but this time it is quite different.

Usually currying routines use fn.length to determine how far the currying should go. This is rather restricting.

Some other modules do something trickier than that, but you still can't effect their choices from inside a function being curried.

Gain full control

curry = require('dyn-curry')

curry([ctx], fn)

Returns a wrapper function.

Inside fn, return curry to indicate that the function needs more arguments. It shouldn't usually produce any side effects, because the wrapper will be called each time new chunk of arguments is supplied. Return fast.

Finally, curry is curried itself! If the first argument is not a function, it will wait for the function to come. (Be careful: if the context is a function indeed, you should pass all of the arguments at once, no currying will happen — sorry!)

Examples

Optional arguments

var hello = curry(function (options, message) {
  if (typeof options == 'string') {
    // No options - return the message.
    return options;
  }
  if (message == null) {
    // No message - curry.
    return curry;
  }
  // Both options and message - format the message and return.
  return (options.prefix || '') + message + (options.suffix || '');
});

hello('Hello!'); // "Hello!"
hello({ suffix: ' Nice jacket!' }); // function
hello({ suffix: ' Nice jacket!' })('Hello!'); // "Hello! Nice jacket!"

Simulating traditional currying

var add = curry(function (a, b) {
  if (arguments.length < 2) {
    return curry;
  }
  return a + b;
});

add(); // function
add(1); // function
add(1, 2); // 3

String concatenation

var makeSentence = curry(function () {
  var last = arguments[arguments.length - 1];
  if (typeof last != 'string' || last[last.length - 1] != '.') {
    // Curry until the sentence ends.
    return curry;
  }
  return [].join.call(arguments, ' ');
});

var sentence = makeSentence('Master', 'Foo'); // function
sentence = sentence('was', 'iterating'); // function
sentence = sentence('along', 'the', 'beach.'); // finally, a string

Blackjack

var blackjack = curry(function () {
  var value = [].reduce.call(arguments, function (a, b) {
    return a + b;
  }, 0);
  return (value < 21) ? curry : value;
});

blackjack(10); // function
blackjack(10)(11); // 21
blackjack(10)(5, 3)(2, 1); // 21
blackjack(42); // 42

Install

npm install dyn-curry

License

MIT