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

[arthur miller <arthur.miller@live.com>]

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>   I rather agree with Joost on that other thread regarding the
>   usefulness of the FOO-let macros and their condition-only,
>   non-binding clauses.
>
>I don't think anyone is arguing about their usefulness, only that the
>macros are too smart for their own good.

I think I will start argue against while-let usefulness :).

Now when I have seen that while-let is a special case of named-let,
I think that while-let is a bad construct for some reasons:

1. it is not general
2. the special case in which it does not work is hidden
3. the semantic of "read-only" loop variables is uncommon and unexpected

>   > There is no mention of this in the manual, that only says that SPEC is
>   > like the one in LET*.

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.

>   But I agree with you that the manual is incomplete or even
>   wrong here.

If that semantic of while-let is desirable to have, than the manual would
have to catch the details of while-let and its non-general nature, read-only
semantic of bindings and perhaps mention the named-let as a more general
 alternative.

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