Zachary Beane wrote:

> (defun mapcar-pos+ (list)
> (let ((i -1))
> (mapcar #'(lambda (elt) (+ elt (incf i)))

Truly abysmal ignorance or willful stupidity.

The #' is redundant.

>
> > iteration:
> >
> > (defun pos+ (lst)
> > (setf acc NIL)
> > (setf i 0)
> > (dolist (obj lst)
> > ; i know, instead of append, i could do a cons and reverse afterwards...
> > (progn (setf acc (append acc (list (+ obj i))))
> > (setf i (+ i 1))))
> > acc)
>
> I'd prefer LOOP here:
>
> (defun loop-pos+ (list)
> (loop for i from 0
> for elt in list
> collect (+ elt i)))

Gauche Scheme:

(define (pos+ input)
(@ (i -1) map x : (+ x (++ i)) input))

(pos+ '(900 800 700 600 500))
===>
(900 801 702 603 504)

Given:

(define ++ inc!)

(define-syntax @-aux
(syntax-rules (:)
[(_ () goodlets func (vars ...) : expr lst ...)
(let* goodlets (func (lambda (vars ...) expr) lst ...))]
[(_ () goodlets func (vars ...) var more ...)
(@-aux () goodlets func (vars ... var) more ...)]
[(_ (var val more ...) (goodlets ...) stuff ...)
(@-aux (more ...) (goodlets ... (var val)) stuff ...)]))

(define-syntax @
(syntax-rules ()
[(_ (lets ...) func stuff ...)
(@-aux (lets ...) () func () stuff ...)]
[(_ func stuff ...)
(@ () func stuff ...)]))