Comment by kazinator

Given the existence of exception handling, I would rather apply the pattern:

   ;; Plain old ANSI Lisp

   (let* ((x (or (foo) (error "..."))))
          (y (or (bar x) (error "bar ..."))
          ...)
     body)

I mean, if, in the end, we are going to "error out", rather than just forward-propagate `nil`.

If we are going to just propagate `nil`, then if we have an `iflet` that tests the last variable, we can do:

  (iflet ((x (expr))
          (y (if x (bar x))
          (z (if y (foo x y))) ;; z is tested by iflet
    ...)

it's just a bit verbose. That can be condensed with a simpler macro that doesn't have the err stuff.