lisptips:

There are two means of automatic initialization of CLOS slot values, :initform and :default-initargs. Chris Riesbeck makes a strong case for preferring :default-initargs.

Here’s a simplified example of the syntactic difference, taken from some Quicklisp code. Consider modeling version control…

slime-tips:

After updating Slime it’s usually needed to restart Emacs so that the changes take effect, but restarting Emacs is quite inconvenient. After adding the following code into .emacs, M-x restart-slime will reload all the Emacs Lisp parts (CL side should be restarted with ,restart short-cut in the…

lisptips:

parse-integer takes :start and :end arguments, so you don’t have to extract integer subsequences from strings to pass them to parse-integer. For example, to parse date strings that look like “2011-10-01” into year, month, and date integers, you can do this:

(defun parse-date (string) "Parse a...

slime-tips:

M-x slime-list-threads (you can also access it through slime-selector shortcut t) will list running threads by their names, and their statuses.

The thread on the current line can be killed with k, or if there’s a lot of threads to kill, several lines can be selected and k will kill all the…

slime-tips:

Slime has a nice cross referencing facility, for example, you can see what calls a particular function or expands a macro.
It presents a list of places which reference a particular entity, from there you can recompile the thing which references by pressing C-c C-c on that line. C-c C-k will…

slime-tips:

M-x slime-format-string-expand: expands the format control string at point.

”~a, ~a.” on SBCL yields

#'(LAMBDA (STREAM &OPTIONAL (#:FORMAT-ARG1502 (ERROR 'SB-FORMAT:FORMAT-ERROR :COMPLAINT "required argument missing" :CONTROL-STRING "~a, ~a." :OFFSET 1)) (#:FORMAT-ARG1503 (ERROR...

lisptips:

To create an empty file, like the Unix touch command does, you might try something like this:

;; BOGUS
(close (open "foo.txt" :direction :output :if-does-not-exist :create :if-exists :append))

open has a :direction option specifically for this purpose, though:

(open "foo.txt" :direction :probe

lisptips:

The naive way to swap the values of two places, a and b, is something like this:

;; BOGUS
(setf temp a)
(setf a b)
(setf b temp)

psetf (parallel setf) can do it in one form:

(psetf a b b a)

But rotatef is best:

(rotatef a b)

slime-tips:

Slime has many buffers, and sometimes it’s not easy navigating between them, slime-selector simplifies this task.
It’s not bound to any key by default, I bind it globally to C-z

(global-set-key "\C-z" 'slime-selector)

Then it allows you to select a buffer by a letter.
Some of the most useful shortcuts are listed here, the full list can be seen by pressing “?”.

• r   Current active REPL
• l    Most recently visited lisp file
• d   Debugger 
• c   List of implementations slime is connected to
• t   Threads list
• i   *inferior-lisp* buffer
• s    *slime-scratch* buffer (for writing one-off code)
• v   Log of slime events (useful for debugging Slime problems)