bug#73853: 31.0.50; and-let* is useless

bug#73853: 31.0.50; and-let* is useless

[Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors]

Package: Emacs
Version: 31.0.50


According to its docstring, `and-let*` does:

    Bind variables according to VARLIST and conditionally evaluate BODY.
    Like `when-let*', except if BODY is empty and all the bindings
    are non-nil, then the result is the value of the last binding.

IOW the only time it's different from `when-let*` is when BODY is empty,
i.e. its only "feature" compares to `when-let*` is that

    (and-let* (..BINDINGS..
               (last (binding))))

is equivalent to

    (and-let* (..BINDINGS..)
      (binding))

Why would anyone write the first instead of the second, other than out
of masochism?  Can we kill/deprecate this?
[ I think we have too many (if|when|and)-let(*) for our own good: we
  should pick some winners and deprecate the other ones.   ]

I could see a use for something called `and-let(*)` but without a BODY,
for the purpose of remove a level of parens and indentation:

    (and-let*
      (x1 (foo1))
      (x2 (foo2)))

i.s.o

    (and-let*
        ((x1 (foo1))
         (x2 (foo2))))


- Stefan

bug#73853: 31.0.50; and-let* is useless

[Drew Adams via Bug reports for GNU Emacs, the Swiss army knife of text editors]

> [ I think we have too many (if|when|and)-let(*) for our own good: we
>   should pick some winners and deprecate the other ones.   ]

+1.

(Are there really any winners? ;-))

bug#73853: 31.0.50; and-let* is useless

[Michael Heerdegen via Bug reports for GNU Emacs, the Swiss army knife of text editors]

Stefan Monnier via "Bug reports for GNU Emacs, the Swiss army knife of
text editors" <bug-gnu-emacs@gnu.org> writes:

> Can we kill/deprecate this?

`and-let*'s purpose is to express conditions, `when-let*'s is
conditional evaluation.  We have `and-let*' and `when-let*' for the same
reason we have `and' and `when'.  See prior discussions.

> [ I think we have too many (if|when|and)-let(*) for our own good: we
>   should pick some winners and deprecate the other ones.   ]

AFAIR the non-star versions exist for backward compatibility only - so I
would rather get rid of these.  Parallel existence of these non-star
vs. star versions should be a temporary state, it complicates the matter
for an epsilon gain.

> I could see a use for something called `and-let(*)` but without a BODY,
> for the purpose of remove a level of parens and indentation:
>
>     (and-let*
>       (x1 (foo1))
>       (x2 (foo2)))
>
> i.s.o
>
>     (and-let*
>         ((x1 (foo1))
>          (x2 (foo2))))

Ugh! - I could not imagine anything with more potential for confusion as
removing the paren around a list of bindings.  This would add one more
year-lasting round of discussing these constructs.  If you do this,
please call it `and-let*?@!' so than everybody is warned.


Michael.