[iterate-devel] value of the top-level restriction?

[Hoehle, Joerg-Cyril]

Hi,

why are some forms restricted to top-level, while others are not?

For example, the following looks like a good replacement of FOR IN which is not restricted to top-level iteration:

(iter (repeat 5)
      (let () ;  not at top-level
        (with l = '(1 2 3))
        (for el do-next (if (null l) (terminate) (dsetq el (pop l))))
        (princ (cons "hi" el))))
(hi . 1)(hi . 2)(hi . 3)
This could be wrapped via iterate:defxyz and even be used as a generator.

Likewise, the in-whole-vector example in the manual IMHO provides a better iterator than the built-in IN-VECTOR: it is not restricted to top-level -- it uses FOR DO-NEXT.

(iterate(repeat 5)(let()(for x in-vector #(1 2 3))(princ x)))
Iterate, in (FOR X IN-VECTOR #(1 2 3)):
Clause can occur only at top-level
   [Condition of type SIMPLE-ERROR]

Does anybody know the reason of the top-level check?
Is it a kind of user safeguard?

Should the meaning of "TOP-LEVEL" in Iterate be redefined?

Regards,
	Jörg Höhle.