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Re: [Emacs-diffs] master 4612b2a 1/2: Implement and-let*

From: Michael Heerdegen
Subject: Re: [Emacs-diffs] master 4612b2a 1/2: Implement and-let*
Date: Thu, 14 Sep 2017 17:46:45 +0200
User-agent: Gnus/5.13 (Gnus v5.13) Emacs/26.0.50 (gnu/linux)

Richard Stallman <address@hidden> 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.


`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.


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