Re: problem with mapconcat

[Kevin Rodgers]

Christian Wittern wrote:
> I am trying to build a regex with lisp, which inserts a certain string 
> into another string between each character, for example "abc" should 
> turn into "a/b/c". 
>
> With mapconcat, I think this should work:
>
> (mapconcat 'identity (string-to-list "abc") "/")
>
> since the description for mapconcat says
>
> (mapconcat FUNCTION SEQUENCE SEPARATOR)
>
> However, when I try to evaluate this in Emacs 23.1, here it throws the 
> following error:
>
> Debugger entered--Lisp error: (wrong-type-argument sequencep 97)
>   mapconcat(identity (97 98 99) "/")
>   eval((mapconcat (quote identity) (string-to-list "abc") "/"))
>
> I wonder what I am doing wrong or if there is another way to achieve
>  what I am trying to do.

The reason your first attempt failed is that string-to-list returns a list of
characters, and identity obviously returns each character -- but mapconcat
requires that FUNCTION return a string.

As Thamer Mahmoud showed, string-to-list is unnecessary:

(mapconcat 'char-to-string "abc" "/")

--
Kevin Rodgers
Denver, Colorado, USA