lisp

I'm just playing around with scheme/lisp and was thinking about how I would right my own definition of average . I'm not sure how to do some things that I think are required though. define a procedure that takes an arbitrary number of arguments count those arguments pass the argument list to (+) to sum them together Does someone have an example of defining average ? I don't seem to know enough about LISP to form a web search that gets back the results I'm looking for. The definition would be a very simple one-liner, but without spoiling it, you should look into: a "rest" argument -- this

Suppose we use SBCL's #'save-lisp-and-die to create an server applicatioon App1, which works very well. Now we want to replace a function #'func1 with a new version without stopping App1. How can we do it in Common Lisp ? Any suggestion is appreciated ! You need to load the new function definition. Then new function will be available immediately; code will call newly loaded function. New function definition may be loaded in many ways: (load (compile-file "file.lisp")) where file.lisp is a source code for function (load "file.fasl") where file.fasl is compiled source code (eval (defun ...)) Of

Several times I came across the notion of uninterned symbols, but I am not entirely clear about what they are. Is there a way to intern a symbol created with (make-symbol)? Can I assign a value to a symbol without interning it? Is it possible to rename a symbol (interned or uninterned)? What else can one do with an uninterned symbol? Update: What is happening with symbols in this piece of code? CL-USER> (defun func () (let ((var 'sym)) (print (find-symbol "sym")) (print var))) FUNC CL-USER> (func) NIL SYM SYM My incorrect understanding is: 1. find-symbol prints nil, so the symbol is not

I have a list of elements '(a b c) and I want to find if (true or false) x is in it, where x can be 'a or 'd, for instance. Is there a built in function for this? If you need to compare using one of the build in equivalence operators, you can use memq , memv , or member , depending on whether you want to look for equality using eq? , eqv? , or equal? , respectively. > (memq 'a '(a b c)) '(a b c) > (memq 'b '(a b c)) '(b c) > (memq 'x '(a b c)) #f As you can see, these functions return the sublist starting at the first matching element if they find an element. This is because if you are

If I have a list like this ((0 1 2) (3 4 5) (6 7 8) (0 3 6) (1 3 7) (2 4 8) (0 4 8) (2 4 6)) And I want to find the index of (0 3 6) , is there a built-in function to do this? POSITION doesn't seem to work when the search item is itself a list. See hyperspec . POSITION can take a :test argument: (position '(0 3 6) '((0 1 2) (3 4 5) (6 7 8) (0 3 6) (1 3 7) (2 4 8) (0 4 8) (2 4 6)) :test #'equal)) 3 The default test for POSITION (and other sequence operations) is EQL, by the way. 来源： https://stackoverflow.com/questions/4288292/get-index-of-list-within-list-in-lisp

I binded function semantic-symref to key C-c C-r like this: (global-set-key (kbd "C-c C-r") 'semantic-symref) everytime I pressed C-c C-r , it prompted: Find references for xxxxx? (y or n) How can I answer it automatically? I tryed using lambda function like this, but failed (global-set-key (kbd "C-c C-r") (lambda() (interactive) (semantic-symref "yes"))) The answer by @huitseeker is quite neat and effective. After four years, with flet and defadvice being obsolete, I wrote the following functions to answer yes automatically. Maybe it's useful for someone. (defun my/return-t (orig-fun &rest

I have a hash table where the keys are rather complex lists, with sublists of symbols and integers, and the value should be modified depending on the already existing value. The table is created with :test #'equal . I do something similar to this a lot: (defun try-add (i) (let ((old-i (gethash complex-list table nil))) (if (may-add old-i) (push i (gethash complex-list table))))) Profiling shows that equal tests take a lot of time. I have an optimization idea, that the amount of gethash lookups could be reduced from two to one. It can be done in C++ by reusing the iterator, but not sure how