Hacker News Reader

Comment by Peaker | Hacker News Reader

They seem to simply be missing flip.

  // Lets curry subtract instead of add
  var subtract = Udon.curry(function(a, b) {
      return a - b;
  });

  var five_minus = subtract(5);
  var minus_five = Udon.flip(subtract)(5)

View on HN

Yes, although there is one subtlety here: should `flip` return a curried function, or an uncurried function? This isn't an issue in Haskell since it only has unary functions.

Haskell has tuples, so it could use an:

  (a, b) -> c

representation. If the uniform/canonical way to use functions is defined to be curried, then flip can simply return them curried.

> Haskell has tuples, so it could use an:

Which it does:

    curry :: ((a, b) -> c) -> a -> b -> c

    uncurry :: (a -> b -> c) -> (a, b) -> c

How about both?

  Udon.flip = function(f) {
      return function(x) {
          if(arguments.length > 1) {
              return f(arguments[1])(x);
          }
          return function(y) {
              return f(y)(x);
          };
      };
  };

Reply on news.ycombinator.com