bug#22961: The read function does not support a lambda argument

[Mihai Călin Bazon]

You should (setq lexical-binding t) before running it (and note that's buffer-local, I've been bitten by that several times).  With lexical binding my original example should work (with the fix, as John pointed out, that the argument should be &optional).

Thanks Andreas for the quick fix! :-)

On Wed, Mar 9, 2016 at 10:31 PM, Kaushal Modi <kaushal.modi@gmail.com> wrote:

I just re-built using this commit ( http://git.savannah.gnu.org/cgit/emacs.git/commit/?h=emacs-25&id=711ca362e7f8ca7c4f664dc2fe60bc5fa4e4f4fe ).

Now the earlier error went away, but I get 

  Symbol’s value as variable is void: prev

I guess the read call should be inside the let:

(let ((str "TEST")

      (pos 0)

      (prev nil))

  (read (lambda (&optional ch)

          (cond

           (ch (push ch prev))

           (prev (pop prev))

           ((< pos (length str))

            (prog1 (aref str pos)

              (setq pos (1+ pos))))))))

Above returns "TEST".

--

Mihai Bazon,
http://lisperator.net/