Subject: Re: bug#22101: Emacs-25: inaccuracy in documentation of `mapconcat' in .../lispref/functions.texi
From: Alan Mackenzie <[email-masked]>
To: Eli Zaretskii <[email-masked]>
Cc: [email-masked]
Date: Mon, 7 Dec 2015 10:54:58 +0000
List-Id: <debbugs-submit.debbugs.gnu.org>

Hello, Eli.

On Sun, Dec 06, 2015 at 06:04:46PM +0200, Eli Zaretskii wrote:
> > Date: Sun, 6 Dec 2015 10:26:22 +0000
> > From: Alan Mackenzie <[email-masked]>

[ .... ]

> IMO, this errs on the other side: it seems to allow sequences that
> will be rejected by mapconcat or by concat that it calls.  I suggest
> the following alternative wording:

>  @code{mapconcat} applies @var{function} to each element of
>  @var{sequence}; the results, which must be sequences of characters
>  (strings, vectors, or lists), are concatenated into a single string
>  return value.  Between each pair of result sequences,
>  @code{mapconcat} inserts the characters from @var{separator}, which
>  also must be a string, or a vector or list of characters.

>  The argument @var{function} must be a function that can take one
>  argument and return a sequence of characters: a string, a vector, or
>  a list.  The argument @var{sequence} can be any kind of sequence
>  except a char-table; that is, a list, a vector, a bool-vector, or a
>  string.

> WDYT?

I think it's good.  I have just taken the liberty of committing your
version, with two changes: I have added @xref{Sequences Arrays Vectors}
at the end of the first paragraph.  I have changed "return" to "returns"
to indicate that the "returning" is mandatory, and not a subclause of the
"can" bit.  (A small point, but I think it's more correct.)

-- 
Alan Mackenzie (Nuremberg, Germany).