Thanks a second time, I'm getting there! I realized one can look at the transformed javascript output, to see just what it does. The setting of the variable in

Thanks a second time, I'm getting there! I realized one can look at the transformed javascript output, to see just what it does. The setting of the variable in the defer becomes: $.getJSON(url, __iced_deferrals.defer({ assign_fn: (function() { return function() { return json = arguments[0]; }; })(), lineno: 6 })); Presumably, when the function that __iced_deferrals.defer returns is called by the code in .getJSON that delivers the result, it will set arguments[0] to that result, and then call the assign_fn above. This will set json to that result. Also, I realize that it doesn't set json to the returned value of $.getJSON, as $.getJSON doesn't return anything - it uses a callback to deliver its result. It seems that ICS always works this way - which I guess implies that the use-case it's for always uses callbacks... BTW: I'm not sure why the above has a function which is then called immediately. Maybe a coffeescript thing, for separating namespaces? I assume the lineno: 6 is for debugging - I recall some debate against this. Good to see it got in.