Say you want to calculate distances from origin to each point in array, and keep only these greater than R.

Using fors and ifs:

    var origin = Point(0, 0);
    var R = 100;
    var result = [];
    for (var i : array) {
        tmp = distance(array[i], origin);
        if (tmp>R) {
           result.append(tmp);
        }
    }

Without currying (nobody would write it that way):

    var origin = Point(0, 0);
    var R = 100;
    result = filter( map(array, function (x) { return distance(x, origin); }),
                     function (x) { return greater(x, R);} );

With currying it almost reads like SQL:

    var origin = Point(0, 0);
    var R = 100;
    result = filter( map(array, distance(origin)), greater(R) );

It's useful for functions that you predict will be used many times with one of the arguments the same. Yes, it's just syntactic sugar, but it sometimes makes code clearer (especially when literal function syntax is as verbose as in javascript).