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

[Jens Schmidt <jschmidt4gnu@vodafonemail.de>]

This turned out to be a discussion orthogonal to the one
on while-let, so I think it deserves its own thread ...

On 2024-11-10  12:44, Alfred M. Szmidt wrote:

> If this is useful or not is one thing, but clearly these macros try to
> be too "smart" and don't follow their own description of what they do
> in either docstring or manual.

I rather agree with Joost on that other thread regarding the
usefulness of the FOO-let macros and their condition-only,
non-binding clauses.

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

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

How about the following in section "Conditionals" instead
of what there currently is about these:

  There's a number of variations on this theme, and they're briefly
  described below.

  For all of these SPEC is similar to what let* offers, with a few
  extensions useful in the context of testing conditions: As with
  let*, an element of SPEC which is a list (SYMBOL VALUEFORM) binds
  SYMBOL to the value of VALUEFORM.  An element can additionally be
  of the form (VALUEFORM), which is evaluated and checked for nil;
  i.e. SYMBOL can be omitted if only the test result is of
  interest.  It can also be of the form SYMBOL, then the binding of
  SYMBOL is checked for nil.

   -- Macro: if-let spec then-form else-forms...
       Evaluate each binding in SPEC in turn, stopping if a binding
       value or value form is ‘nil’.  If all are non-‘nil’, return
       the value of THEN-FORM, otherwise the last form in
       ELSE-FORMS.

   -- ...

If needed, I can provide that or something similar as a patch ...