1

I ran the following code to print 15 sequential values of i both in the scratch buffer and the ielm repl:

    (defvar i 0)
    (while (< i 15)
       (print i)
       (setq i (+ i 1)))`

What I noticed in both the scratch buffer and the repl, is that they both only show the resulting value of the sexp. The printed values of i are then sent to the Messages buffer.

  1. At least for the repl, how can I get the values of i printed in the repl?
  2. If you have other solutions that have worked well for you, please let me know!

Note that I use emacs 24.3 through the terminal and Ubuntu 12.04 LTS. Thanks for all the help!

Additionally, From the documentation of print we have:

print is a built-in function in `C source code'.

(print OBJECT &optional PRINTCHARFUN)

Output the printed representation of OBJECT, with newlines around it.
Quoting characters are printed when needed to make output that `read'
can handle, whenever this is possible.  For complex objects, the behavior
is controlled by `print-level' and `print-length', which see.

OBJECT is any of the Lisp data types: a number, a string, a symbol,
a list, a buffer, a window, a frame, etc.

A printed representation of an object is text which describes that object.

Optional argument PRINTCHARFUN is the output stream, which can be one
of these:

   - a buffer, in which case output is inserted into that buffer at point;
   - a marker, in which case output is inserted at marker's position;
   - a function, in which case that function is called once for each
     character of OBJECT's printed representation;
   - a symbol, in which case that symbol's function definition is called; or
   - t, in which case the output is displayed in the echo area.

If PRINTCHARFUN is omitted, the value of `standard-output' (which see)
is used instead.
  1. As I am new to practical aspects of lisp, how do I print to a different buffer?
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2 Answers 2

Reset to default
3

Here's a tiny extension to Emacs Lisp format I've written to perform similar to Common Lisp format, but using % as the control character:

http://code.google.com/p/formatting-el/source/browse/trunk/formatting.el

So, for example, if you wanted to print a list of numbers with linebreaks into a string, you'd do it like so:

(cl-format "%{%s%^\n%}" (cl-loop for i from 0 below 10 collect i))
"0
1
2
3
4
5
6
7
8
9"

Another way to achieve this would be to use something like this:

(mapconcat #'number-to-string (cl-loop for i from 0 below 10 collect i) "\n")
"0
1
2
3
4
5
6
7
8
9"
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3 Comments

Can't I load common-lisp features from my .emacs file?
@CodeKingPlusPlus I'm not quite sure what are you asking about... Common Lisp is a separate programming language, however, there is a package cl in Emacs Lisp, which provides functions similar to the ones found in its prototype. However, this package doesn't have an analogue to format from Common Lisp, my cl-format function is an attempt to compensate for that omission.
That was what I was asking about. Thanks!
2

You can use with-output-to-string if you really want:

(with-output-to-string
    (setq i 0)
    (while (< i 15)
      (princ i)
      (setq i (+ i 1))))
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10 Comments

How would I print a newline between values of i? Is there some kind of format string?
If you want newline, use print instead of princ
If I do that then with-output-to-string gives me the values of i concatenated with newline characters \n
*scratch* doesn't show the messages buffer if you eval with C-j. Which you should always use in *scratch*, because that's what it's for.
emacs -q says otherwise. It's bound to eval-print-last-sexp. Maybe you've rebound it.
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