Ugly curry adaptation, for handling `new`

gistfile1.js

Function.prototype.curry = function () {
    var slice = Array.prototype.slice,
        args = slice.apply(arguments),
        that = this;

    return function _curried() {
        var fn = Function.prototype.bind.apply(that, args.concat(slice.apply(arguments)));
        fn.prototype = that.prototype;
        if ( this instanceof _curried ) return new fn();
        else                        return fn();
    };
};

var Field = function (type, name, description) {
    this.name = name;
    this.description = description;
    this.type = type;
};

Field.prototype.as_html_field = function () {
    var widget;
    
    switch(this.type) {
        case 'char':
            widget = document.createElement('input');
            widget.setAttribute('type', 'text');
            break;
        case 'int':
            widget = document.createElement('input');
            widget.setAttribute('type', 'number');
            break;
        case 'text':
            widget = document.createElement('textarea');
            break;
        default:
            return 'failed';
    }

    widget.setAttribute('name', this.name);
    widget.setAttribute('placeholder', this.name);
    return widget;
}

var CharField = Field.curry('char');
var TextField = Field.curry('text');
var IntField = Field.curry('int');