From: Michael Heerdegen <michael_heerdegen@web.de>
To: Richard Stallman <rms@gnu.org>
Cc: mvoteiza@udel.edu, Stefan Monnier <monnier@IRO.UMontreal.CA>,
emacs-devel@gnu.org
Subject: Re: [Emacs-diffs] master 4612b2a 1/2: Implement and-let*
Date: Thu, 14 Sep 2017 17:46:45 +0200 [thread overview]
Message-ID: <87y3phcmfu.fsf@web.de> (raw)
In-Reply-To: <E1dsAhX-0001B5-4R@fencepost.gnu.org> (Richard Stallman's message of "Wed, 13 Sep 2017 12:39:47 -0400")
Richard Stallman <rms@gnu.org> writes:
> > > (internal--build-binding-value-form): Extend to account for
> > > solitary symbols and (EXPR) items in binding varlist.
>
> > We're forced to accept those forms in `let` and `let*` for historical
> > reasons,
>
> It is not just a matter of history.
> Those are very convenient in 'let'.
> It would be a bad idea not to have them.
> Whether they are useful in other new constructs, I don't know.
> What do these new constructs look like?
Just search for SRFI 2, e.g.
https://www.gnu.org/software/guile/manual/html_node/SRFI_002d2.html
`if-let*' and `when-let*' in Emacs are analogue.
I don't know much about Lisp's history, but I think there was a
misunderstanding about what these special binding forms mean. For
example, making a binding form consisting of a single symbol mean "bind
the symbol to nil" would not make sense in these new constructs -
instead, we test the symbol's value for nilness.
Michael.
prev parent reply other threads:[~2017-09-14 15:46 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20170912171813.26498.77867@vcs0.savannah.gnu.org>
[not found] ` <20170912171815.13B9520DE6@vcs0.savannah.gnu.org>
2017-09-12 17:21 ` [Emacs-diffs] master 4612b2a 1/2: Implement and-let* Stefan Monnier
2017-09-12 17:29 ` Mark Oteiza
2017-09-13 16:39 ` Richard Stallman
2017-09-14 15:46 ` Michael Heerdegen [this message]
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