Comments on: Evaluating Elisp in Emacs

By: mickey

mickey — Mon, 14 Nov 2011 18:53:00 +0000

Expressions here means that a variety of operations are tried in order to resolve your query to M-: — if you give it a string you’ll get a string back as as strings and numbers evaulate to themselves. A variable will give you its value and a function its output.

The difference between a form and an s-expression is pretty academic:

A form is an s-expression, but an s-exp may not necessarily be a form; for instance, (+ 1 1) is a form but (“+” 1 1) is not as you cannot evaluate the string “+”.

By: mickey

mickey — Mon, 14 Nov 2011 18:45:37 +0000

Oh, yes, perhaps I should clarify: the shell I am referring to is the ielm shell itself.

By: Comrade Curious

Comrade Curious — Sat, 12 Nov 2011 18:04:11 +0000

What is the difference between s-expression, form, and expression?

A form is any top-level s-expression?

“blah”, 123, [1 2 3] are expressions that are not s-expressions?

By: Michael

Michael — Sat, 12 Nov 2011 08:48:29 +0000

Hi Mickey, what do you mean by “useful features you would expect from an interactive shell, like *, ** and *** to get the last three outputs from the shell”? I never heard of this but it sounds interesting. What shell would that be? bash?

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Fun with Vimgolf 2: Sum your vimgolf rank | Mastering Emacs — Thu, 03 Nov 2011 20:35:58 +0000

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By: Conor

Conor — Tue, 02 Aug 2011 23:36:12 +0000

Do you have an example macro or two where you use M-: ?

I haven’t used elisp much but have been using keyboard macros a lot lately.

Just trying to get an idea of the kinds of things I could do with M-:

By: Paul Hobbs

Paul Hobbs — Wed, 08 Dec 2010 23:05:44 +0000

It’s worth mentioning that M-: is REALLY useful when doing keyboard macros.

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Tue, 30 Nov 2010 11:54:36 +0000

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By: Scott

Scott — Mon, 29 Nov 2010 17:32:45 +0000

I use C-M-S-x to do what C-M-x does but for the the immediately enclosing form as opposed to the top-level one. I don't like going to the end and doing C-x C-e. I don't write much emacs lisp so I've only implemented this for slime.

(defun up-list+ ()
  (interactive)
  (if (in-string-p)
      (while (in-string-p)
        (forward-char))
    (up-list)))

(defun eval-parent-sexp ()
  "Cause sometimes you just want to eval just the immediate form. not the top level, but without going to the closing paren and evaling there."
  (interactive)
  (save-excursion
    ;; get out of string if in it
    (dotimes (c (if (in-string-p) 2 1))
      (up-list+))
    (let ((cmd (key-binding (kbd "C-x C-e"))))
      (if (eq cmd 'slime-eval-last-expression)
          (funcall cmd)
        (funcall cmd '())))))

(global-set-key (kbd "C-M-S-x") 'eval-parent-sexp)

By: Reynaldo

Reynaldo — Mon, 29 Nov 2010 15:28:23 +0000

Great post!
I didn’t know about ielm nor C-M-x.
Thanks