Looping over strings gives wrong type argument error in Emacs Lisp

I am trying to loop over a list of strings with dolist, and join element with a prefix string, using string-join from subr-x to create new string.

(dolist (p '("a" "b" "c"))
   (string-join '(p ".rnc")))

I am getting the error Wrong type argument: sequencep, p. The following code however works.

(dolist (p '("a" "b" "c"))
   (print p))

So this seems to be a problem of string-join or equivalently mapconcat within a loop. Any suggestions? Thanks!


  • '(p ".rnc")

    It's very important to understand that '... which means (quote ...) is not a shorthand for making lists.

    It's a form which causes lisp to return, unevaluated, the object that was created by the lisp reader.

    In this instance the lisp reader returns a list containing the symbol p and a string ".rnc" -- and the symbol p is indeed not a sequence (hence your error).

    Use (list p ".rnc") to create a list using the evaluated value of p as a variable.

    p.s. Be sure to go over the distinct read and eval phases of lisp execution. Once you understand the distinction, quote will make much more sense.