mew.js

(function (global)
{
    
    var expr = function (n)
    {
        var utilities = {
            "+": function (a, b) { return a + b; },
            "-": function (a, b) { return a - b; },
            "*": function (a, b) { return a * b; },
            "/": function (a, b) { return a / b; }
        };
        
        return function outer(op)
        {
            if (op === "=")  return n;
            
            return function (m)
            {
                n = utilities[op](n, m);
                return outer;
            }
        };
    };
    global.expr = expr;
    
})(window);
 
console.log( expr(4)("+")(3)("*")(2)("-")(1)("=") );