LispForum

I use a non-standard dvorak varient called Programmers Dvorak http://www.kaufmann.no/roland/dvorak/ . I further modified it by swapping 'u' and 'i', and making CAPSLOCK just a third CTRL button. My parenthesis are under keys '5' and '8', but I don't have to hold shift to get them. This is a file I c...

Yeah, I use that too --- Its often inconvenient that last returns a list rather than an item. Maybe I'll just define a utility function
and be done with it.

I actually wrote a blog post on writing parsers: http://formlis.wordpress.com/2010/07/07/flexible-parsing-without-regexps/ . This operation is non-trivial; there are three 3 states: Reading Text, Skipping Whitespace, and Handling Quotes. There are also three diferent character classes: Regular chara...

Why would you want floats/decimal numbers? You could opt to use the more accurate rational numbers throughout your code and then use format's "~f" operator to print the result as a floating point number.

Now here is a working 'reduce' example: (defun average (lst) (/ (reduce #'+ lst :key #'(lambda (x) (first (last x)))) (length lst))) The :key argument tells 'reduce' to which element from the lists inside 'lst' the '+' function shall be applied. Because 'last' returns the last element as a list, th...

I'll yield the point on the names of CAR and CDR. I thought they were a Lisp machine terminology for some dedicated hardware that performed list operations. But my point was never that register machines can't host Lisp, but that their base vocabulary is orthogonal to Lisp. If you want a low-level Li...

Well, not anything too interesting. The results are highly dependent on the heuristic for deciding 'best'. For example, a set of coins that had denominations for 1, 2, 3, 4, 5, 6 ... , 97, 98, 99, 100 would perform well -- only 1 coin is ever needed. If you add a cost for the number of unique coins,...

Here are 5 ways of doing it. I added timing for SBCL on my computer without tweaking any optimization stuff. ;; using a reduction (defun odd-count1 (list) (reduce #.(lambda (acc i) (if (oddp i) (1+ acc) acc)) list :initial-value 0)) ;; using 'loop' (defun odd-count2 (list) (loop for i in list counti...

I actually did this yesterday. I wanted to run a genetic algorithm to see what set of 'coins denominations' made for the least amount of change. Anyway, here was mine: (defun currency (a amounts results) (if (null amounts) (nreverse (cons a results)) (multiple-value-bind (n remainder) (truncate a (c...