Thomas A. Russ wrote:

> > (loop with x = (make array 6 :fill-pointer 0)
> > for i from 0 to 10 by 2 do (vector-push i x)
> > finally return x)
>
> Actually, the finally clause needs to be (return x) instead.
>
> But if you already assume you know the size of the final array, you can
> dispense with the fill pointer and extension and just set it directly:
>
> (loop with x = (make array 6)
> for val from 0 to 10 by 2
> as index upfrom 0
> do (setf (aref x index) val)
> finally return x)

Testing in SBCL:

* (loop with x = (make array 6)
for val from 0 to 10 by 2
as index upfrom 0
do (setf (aref x index) val)
finally return x)

debugger invoked on a SB-INT:SIMPLE-PROGRAM-ERROR in thread
#<THREAD "main thread" RUNNING {23EAC1B9}>:
A compound form was expected, but RETURN found.
current LOOP context: FINALLY RETURN X.

Gauche Scheme

(list->vector (iota 6 0 2))
===>
#(0 2 4 6 8 10)

Another way.

(vector-tabulate 6 (cut * 2 <>))