Passing refs with delegates

[Mark J Twain via Digitalmars-d-learn]

It's nice to be able to pass delegates and functions as callbacks.

A nice feature is something like

R foo(R,Args...)(R function(Args) callback, Args args) { return 
callback(args); }

There are two problems with this.

One is that type deduction doesn't work. I have to explicitly 
specify the types of args. This creates a lot of verbosity. 
Second, I can't pass ref parameters. The usefulness of this 
method is that it sort of lets you pass data in and out of the 
callback, all defined by the user calling foo. Sometimes you want 
to pass in references to store data and other times you don't.

Is this a bug in D's type checking system or unfinished work or 
simply nonsense?

right now I pass in pointers, but that doesn't work to well for 
some types, and is messy.