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bug#28254: 26.0.50; SRFI-2 and-let*
From: |
Michael Heerdegen |
Subject: |
bug#28254: 26.0.50; SRFI-2 and-let* |
Date: |
Sun, 03 Sep 2017 19:48:13 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/26.0.50 (gnu/linux) |
Noam Postavsky <npostavs@users.sourceforge.net> writes:
> On Sat, Sep 2, 2017 at 9:36 AM, Mark Oteiza <mvoteiza@udel.edu> wrote:
> > On 02/09/17 at 07:25am, Michael Heerdegen wrote:
> >>
> >> Isn't there a problem with EXPR being a symbol S, which already has a
> >> different meaning (bind S to nil)? Though, this seems barely
> >> useful to
> >> me. Anyway, introducing (EXPR) would thus be backward incompatible.
>
> What would be the point of binding S to nil? In the foo-let macros
> that would be equivalent to just putting nil (if non-list EXPRs are
> supported), no?
Eh hmm - yes, I think so. It isn't useful.
> I think I'd be okay with dropping support for the S = (S nil) thing in
> foo-let macros, so that all of the above would give (void-variable x).
> Although perhaps the incompatibility with plain let would be annoying?
> To be honest I hardly ever make use of S = (S nil) in plain let either
> so it wouldn't hit me at all.
I think the main use case is to declare a local variable when you don't
care about the init value. In the case of if-let, S = (S nil) is not
useful, since you can't use that binding neither in the "then" clause
(because it won't be executed) nor in the "else" clauses (which ignore
all bindings).
Even if an `if-let' form is the result of a macro expansion, the S = (S
nil) case isn't of any value. So I see no reasons to not drop support
for it.
Michael.
- bug#28254: 26.0.50; SRFI-2 and-let*, Mark Oteiza, 2017/09/01
- bug#28254: 26.0.50; SRFI-2 and-let*, npostavs, 2017/09/01
- bug#28254: 26.0.50; SRFI-2 and-let*, Mark Oteiza, 2017/09/02
- bug#28254: 26.0.50; SRFI-2 and-let*, Michael Heerdegen, 2017/09/02
- bug#28254: 26.0.50; SRFI-2 and-let*, Mark Oteiza, 2017/09/02
- bug#28254: 26.0.50; SRFI-2 and-let*, Noam Postavsky, 2017/09/02
- bug#28254: 26.0.50; SRFI-2 and-let*,
Michael Heerdegen <=
- bug#28254: 26.0.50; SRFI-2 and-let*, Mark Oteiza, 2017/09/03
- bug#28254: 26.0.50; SRFI-2 and-let*, Mark Oteiza, 2017/09/03
- bug#28254: 26.0.50; SRFI-2 and-let*, Michael Heerdegen, 2017/09/04
- bug#28254: 26.0.50; SRFI-2 and-let*, Mark Oteiza, 2017/09/04
- bug#28254: 26.0.50; SRFI-2 and-let*, Michael Heerdegen, 2017/09/05
- bug#28254: 26.0.50; SRFI-2 and-let*, Michael Heerdegen, 2017/09/06
- bug#28254: 26.0.50; SRFI-2 and-let*, Mark Oteiza, 2017/09/06
- bug#28254: 26.0.50; SRFI-2 and-let*, Michael Heerdegen, 2017/09/06
- bug#28254: 26.0.50; SRFI-2 and-let*, Mark Oteiza, 2017/09/03
- bug#28254: 26.0.50; SRFI-2 and-let*, Mark Oteiza, 2017/09/04