A macro dealing with recursion

Thanks for the great work!
I am thinking of extending it a little. I wrote a "macro" dealing with recursions, so that the user can simply write recursions in the natural way without worrying the fixpoint combinator, and memoize it by wrapping it with the macro, like

```Haskell
$(memoizeRec [d|
    fib :: Int -> Integer
    fib 0 = 0
    fib 1 = 1
    fib n = fib (n-1) + fib (n-2)
  |])

main = print $ fib 1000 -- fast
```

Since it is already using Template Haskell, I guess it is not too bad to use a little more.

Let me know what you think, and if you like I can write a little more, e.g. documentation, more arity support. Sorry that I am not able to type the unicode characters.