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

[arthur miller]

>   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.