What useful R package doesn't currently exist? [closed]

Answer 1

I would like to see a possibility to embed another programming language within R in a more straightforward way by the users. I give this as an example in some common-lisp implementations one could write a function with embedded C code like this:

(defun sample (x)
  (ffi:c-inline (n1 n2) (:int :int) (values :int :int) "{
    int n1 = #0, n2 = #1, out1 = 0, out2 = 1;
    while (n1 <= n2) {
      out1 += n1;
      out2 *= n1;
      n1++;
    }
    @(return 0)= out1;
    @(return 1)= out2;
    }"
   :side-effects nil))

It would be good if one could write an R function with embedded C or lisp code (more interested in the latter) in a similar way.