lisp

I am struggling a little trying to figure out how to tell Lisp that I want to use double-float values. Suppose I have: (let ((x 1)) (format t "~A~%" (/ x 3.0))) Which gives: 0.33333334 If I want to use double-float, I tried this: (let ((x 1)) (declare (type double-float x)) (format t "~A~%" (/ x 3.0))) 0.33333334 So the result is not a double-float. I can, however, force double-float like this: (let ((x 1)) (format t "~A~%" (/ x 3.0d0))) 0.3333333333333333d0 And now I get a double-float result. So my question is: if I'm defining a form or function in which I want arithmetic to be in double

Is it possible to write a Common Lisp macro that takes a list of dimensions and variables, a body (of iteration), and creates the code consisting of as many nested loops as specified by the list? That is, something like: (nested-loops '(2 5 3) '(i j k) whatever_loop_body) should be expanded to (loop for i from 0 below 2 do (loop for j from 0 below 5 do (loop for k from 0 below 3 do whatever_loop_body))) Follow up As huaiyuan correctly pointed out, I have to know the parameters to pass to macro at compile time. If you actually need a function as I do, look below. If you are ok with a macro, go

In the following when macro: (defmacro when (condition &rest body) `(if ,condition (progn ,@body))) Why is the there an at sign? It's very easy to see the difference by making a little experiment > (let ((x '(1 2 3 4))) `(this is an example ,x of expansion)) (THIS IS AN EXAMPLE (1 2 3 4) OF EXPANSION) > (let ((x '(1 2 3 4))) `(this is an example ,@x of expansion)) (THIS IS AN EXAMPLE 1 2 3 4 OF EXPANSION) As you can see the use of ,@ will place the elements of the list directly inside in the expansion. Without you get instead the list placed in the expansion. The @ can also be thought of

I would like to know where I should save my .sbclrc file. I tried saving it in my .sbcl folder, but it doesn't seem to be working. I'm using Windows XP with Emacs version 23. I'm trying to set up asdf-install, that is why I'm mucking around with the initialization file. Thanks for your time. What is the result of evaluating this in the repl: (SB-IMPL::USERINIT-PATHNAME) 来源： https://stackoverflow.com/questions/2245854/sbcl-initialization-file

Is there any synergy between learning different Lisp languages? I'm currently learning Emacs Lisp, as it is immediately useful in my daily Emacs usage, however i'm fascinated with all Lisps, so maybe someday i will learn and use others. Will learning Emacs Lisp help me, when i start digging in Common Lisp, Scheme or Clojure? In other words, will it be for me like learning a completely new language, or some notions and paradigms are common? I'm also interested in comparison of unique differences between the Lisps, which will be a problem, when i come from one Lisp to another. In How to go about