> default values for function parameters

    function f(a, b, c, d)
        a = a or 1
        b = b or 2
        c = c or 3
        d = d or 4
    end

> list comprehensions

https://news.ycombinator.com/item?id=14444215

> local is default, not global

I think this is a con.

> a simple class system if you need it

I also think this is a con, because it limits flexibility.

Here's my class system:

    Object = {}
    function Object:new()
        local self = setmetatable({}, {__index = self})
        return self
    end

And how to use it:

    local super = Object
    Shape = Object.new(super)
    function Shape:new(color)
        local self = super.new(self)
        self.color = color
        return self
    end

    local super = Shape
    RedShape = Object.new(super)
    function RedShape:new()
        local self = super.new(self, 0xff0000)
        return self
    end

If I want to add multiple inheritance, or interfaces, it is easy. Because it is just metatables. With MoonScript this is not possible.

> `export`, `from` and `import` keywords

Sounds like a con to me. `require` is simple.

> `+=`, `/=`, `*=`

I agree with this one.