Re: Fusion Laws?

On 3/30/16 6:17 PM, Michael Haufe wrote:
> In general yes. The exceptions are of course idempotent ones like dom calls which are constant after creation (window.self perhaps?), and innocuous side-effects that are never used:
>
> xs.map(function(x){
> var d = Date.now(); //side-effect
> var r = Math.random(); //side-effect
> return x
> });

The problem is that it's hard to prove functions are side-effect-free in 
JS, in even this weak sense.  For example, your function there might do 
absolutely anything, depending on what's been done to the Date and Math 
properties on the global.  :(

-Boris