Sv: Better documentation for non-binding clauses of if-let and friends

[arthur miller]

>   That is the gotcha that got me: it says SPEC is "like let*", so this "-let*"

>   in the name take my mind to believe it established ordinary let*-bindings.

>   However, in while-let, these are not ordinary, but read-only. So they are

>   not the same, since they don't obey the ordinary behavior of let* bindings.

>

>I agree, but the question really is what should be done -- either

>satisfy one camp or the other.

My guess is while-let can't go away since it is used in many places in Emacs

already. But the docs and the manual can be updated and clarified.

>I personally do not get what one gets from using WHILE-LET -- the

>construct seems forced, and very rare to use.

With the facit in the hand, I agree with you. In practice it saves some typing

in well-chosen contexts. But question is if it is a good practice to have a

construct that seemingly looks like a general let-construct, but really is not.