Are there any #Lisp programmers out there who use a #ScreenReader? Given how messy Lisp can be to read without proper indentation (which I imagne wouldn't translate well on a screen reader) I can't see it is being an easy language to work in without being able to see it.

I've been thinking about a way to make an editor that lets you explore a Lisp program by walking through the forms in the program in a manner similar to the way one might navigate in a MUD. Is this a crazy idea, or one with some merit?

A question for the #lisp folx:
What, if anything, is the difference between #'(lambda ...) and just plain (lambda ...)?

They seem functionally equivalent to me.

(defun lambdamoo-tab-complete ()
  "Complete user input using text from the buffer"
  (interactive)
  (when (memq (char-before) '(?  ?\r ?\n ?\t ?\v))
    (user-error "Point must follow non-whitespace character"))
  (let (replace-start
        (replace-end (point))
        replace-text found-pos found-text)
    (save-excursion
      (backward-word)
      (setq replace-start (point)
            replace-text (buffer-substring replace-start replace-end))
      (when (or (null lambdamoo--search-text)
                (not (string-prefix-p lambdamoo--search-text replace-text t)))
        (setq-local lambdamoo--search-text replace-text)
        (set-marker lambdamoo--found-point (point)))
      (goto-char lambdamoo--found-point)
      (unless
          (setq found-pos
                (re-search-backward
                 (concat "\\b" (regexp-quote lambdamoo--search-text))
                 (point-min) t))
        (setq-local lambdamoo--found-point (make-marker))
        (user-error "No match found"))
      (set-marker lambdamoo--found-point found-pos)
      (forward-word)
      (setq found-text (buffer-substring found-pos (point))))
    (delete-region replace-start replace-end)
    (insert found-text)))

I'm certain I have reinvented a wheel here, but for the life of me I can't find it. Have I?

(defmacro jrl-extract-list (vars list &rest body)
  "Split a list into indiviual variables"
  (let ((list* (gensym)))
    (append
     `(let ,(cons (list list* list) vars))
     (seq-map (lambda (var)
                `(setq ,var (car ,list*)
                       ,list* (cdr ,list*)))
              vars)
     body)))

Edit: Of course it was pcase.

I just put a call to eval in my code and I feel dirty now.

The context went something like this:

(eval (cons 'concat (my-function arg1 arg2)))

(concat . (my-function arg1 arg2))

(concat my-function arg1 arg2)

Is there a better way I could've written this?
#emacs #lisp #elisp

Edit: Got my answer. I wanted:

(apply 'concat (my-func arg1 arg2))

Edit 2:
It turns out the code I really wanted was:

(string-join arg2 arg1)

Edit 3:
Here's the actual code:

(defun lambdamoo-run-text-replacements (str)
  "Perform text replacements on the string"
  (dolist (vals lambdamoo-text-replacements)
    (let* ((from (car vals))
           (to (cdr vals))
           (split (split-string str from)))
      (setq str (string-join split to))))
  str)

(catch :abort
  ;; do something
  (when condition
    (message "A bad thing happened")
    (throw :abort nil))
  ;; do something else
  )

(progn
  ;; do something
  (when condition
    (user-error "A bad thing happened"))
  ;; do something else
  )

#Elisp logic:

All interned symbols can be found in a lookup table. This table is bound to the obarray symbol.

Hang on a minute...

I can only assume that the underlying C code has its own pointer to this table and the obarray symbol is only provided as a convenience for elisp functions that can't see this pointer?
#emacs #lisp

Just spent a good half hour pulling my hair out trying to figure out why one of the #elisp functions I had just written was always returning nil when I tested it. Turns out, my test was mistakenly passing its inputs to the wrong (but similarly named) function (pivot-table-get-columns instead of pivot-table-get-body).

#Haskell's type system would've caught this. 🙃

#emacs #lisp