strange behavior of mapconcat

strange behavior of mapconcat

[shortcutz]

Hi all,

In a piece of code I call mapconcat with these arguments:

(mapconcat 'org-no-properties "t" " ")

I'm getting the error (wrong-type-argument sequencep 115). This is the same
if I use the identity function or any other string instead of "t":

(mapconcat 'identity "t" " ")
(mapconcat 'identity "string1 string2" " ")

What am I doing wrong? I don't really understand where the 115 is coming
from. The code is unchanged after macroexpanding, and sequencep says
"string1 string2" and "t" are both valid sequences.

Thanks
R

Re: strange behavior of mapconcat

[shortcutz]

Oh, sorry my first post is spam....
it is impossible to concatenate two characters! >_<

On Mon, Apr 15, 2024 at 10:43 AM shortcutz <spookygostee@gmail.com> wrote:

> Hi all,
>
> In a piece of code I call mapconcat with these arguments:
>
> (mapconcat 'org-no-properties "t" " ")
>
> I'm getting the error (wrong-type-argument sequencep 115). This is the
> same if I use the identity function or any other string instead of "t":
>
> (mapconcat 'identity "t" " ")
> (mapconcat 'identity "string1 string2" " ")
>
> What am I doing wrong? I don't really understand where the 115 is coming
> from. The code is unchanged after macroexpanding, and sequencep says
> "string1 string2" and "t" are both valid sequences.
>
> Thanks
> R
>

Re: strange behavior of mapconcat

[Michael Heerdegen via Users list for the GNU Emacs text editor]

shortcutz <spookygostee@gmail.com> writes:

> Oh, sorry my first post is spam....
> it is impossible to concatenate two characters! >_<

The FUNCTION argument must return "[...] a sequence of characters" (see
docstring) , so

 (mapconcat #'string "t" " ") ==> "t"

No concatenation involved at all in this example.


Michael.

Re: strange behavior of mapconcat

[Joost Kremers]

On Mon, Apr 15 2024, shortcutz wrote:
> In a piece of code I call mapconcat with these arguments:
>
> (mapconcat 'org-no-properties "t" " ")
>
> I'm getting the error (wrong-type-argument sequencep 115). This is the same
> if I use the identity function or any other string instead of "t":
>
> (mapconcat 'identity "t" " ")
> (mapconcat 'identity "string1 string2" " ")
>
> What am I doing wrong? I don't really understand where the 115 is coming
> from. The code is unchanged after macroexpanding, and sequencep says
> "string1 string2" and "t" are both valid sequences.

They are sequences, but sequences of char (which in Emacs is basically just an
int). What's happening is that the function `org-no-properties` is called on
each element of your string, i.e., on each character, separately. But
`org-no-properties` requires a string as argument, not an int. That's where the
error message is coming from: org-no-properties is saying that it requires a
sequence as argument, but it got the integer 115 (the ASCII value of the
character `t`) instead.

-- 
Joost Kremers
Life has its moments