mew.js

(function (global)
{
    
    var expr = function (n)
    {
        var utilities = {
            "+": function (a) { return function(b){ return a + b; } },
            "-": function (a) { return function(b){ return a - b; } },
            "*": function (a) { return function(b){ return a * b; } },
            "/": function (a) { return function(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)("=") );