Re: Reasons for preferring Lisp, and for what

Joel Ray Holveck wrote:

As a concrete example, suppose (as I did in a program I recently
wrote) that you have a string with several arbitrary variable names
you need to substitute in, and a hash with their values.  This can be
done in one line in Perl:
  # $string holds something like:
  #   'The $dimension of the $obj is $length cm.'
  # %vars holds something like:
  #   { $dimension => length, $obj => plank, $length => 105 }
  $string =~ s/\$(\S+)/$vars->{$1}/g;
 
Now, look at a Lisp parallel.  You have a list, and you want to
substitute keywords with their values from an alist:
  ;; LIST holds something like:
  ;;    (the :dimension of the :object is :value cm)
  ;; VARS holds something like:
  ;;    ((:dimension . length) (:object . plank) (:value . 105))
  (mapcar #'(lambda (elt)
                (if (keywordp elt)
                    (cdr (assoc elt vars))
                    elt))
            list)

newLISP

(define str "The $dimension of the $obj is $length cm.")
(define table '((dimension "length") (obj "plank") (length "105")))

(replace "\$(\w+)" str (lookup (sym $1) table)  0)

"The length of the plank is 105 cm."