Marc,

in _std.scm you have the following code implementing force:

(define-prim (##force obj)
(if (##promise? obj)
      (let ((result (##promise-result obj)))
        (if (##eq? result obj)
            (let* ((r ((##promise-thunk obj)))
                   (result2 (##promise-result obj)))
              (if (##eq? result2 obj)
                  (begin
                    (##promise-result-set! obj r)
                    (##promise-thunk-set! obj #f)
                    r)
                  result2))))

;; XXX -- value is unspecified when (not (##eq? result obj))

obj))

I find it very strange that the first if eq test of the result to the promise is lacking the else part;

that's where I marked with XXX.
Shouldn't the code return result in this case?

What am I missing here?

-- vyzo