After briefly talking about LISP in a past class, I have decided to jump in head first and try to learn CLISP (reading Seibel's PCL chpt 5). My question is in regards to writing a function that takes a set of lists as parameters. The first list is a series of indexes mapped to the second list. I want to pass a sequence of indexes and have it return the corresponding elements.
Here is the outline of my code so far. I wasn't sure if I could use nth and pass a list of arguments to it. I am not sure what the body-form should look like.
sys-info: CLISP 2.49 Win7
(defun get-elements('(nth (x y z) '(a b c)) )
"takes a list of arguments that returns corresponding elements from a list."
(format t "The elements at index ~d are: ~%" x y z)
((maybe indexes go here)'(elements go here?))
The list (x y z) are the indexes and the data list (a b c) is some list of arbitrary elements. The evaluation is passed as data to the function get-elements. Am I even on the right track with this line of thinking?
Hints and pointers to relevant topics in LISP education are greatly appreciated.
postmortem: Upon re-examination of chpts 3-4, it would seem that PCL is a bit of a reach for a beginning programmer (at least for me). I can enter the code from the book, but I obviously don't have a deep understanding of the basic structure of the language. I will probably try a few gentler introductions to Lisp before undertaking PCL again.
I am not quite sure if this is what you are asking about, but you might want to try:
(defun get-nth (index-list data-list)
(mapcar (lambda (index)
(nth index data-list))
index-list))
(get-nth '(0 1 0 2 0 3) '(a b c d e f))
==> (A B A C A D)
Please take a look at
mapcarnthformat call is brokenMore gentle introductions to Lisp: