Embedding multiple Lisp elements in a function programatically

Question

I am messing around with web development and would like to do something like the following:

(defun col1 (&rest content) `((:DIV :CLASS "col1") 
                              (:COMMENT " Column 1 start ")
                              ,content goes here
                              (:COMMENT " Column 1 end ")))

where content is two or more lists returned by a function:

(defun two-list () ....)

that would return

'(:H2 "header")
'(:P "paragraph")

so that

(col1 (two-list))

would return

((:DIV :CLASS "col1") 
 (:COMMENT " Column 1 start ")
 (:H2 "header")
 (:P "paragraph")
 (:COMMENT " Column 1 end "))

I've tried using the values function, but it only seems to embed one list into the content area. Is it possible to do something like this? Thanks for the help lispers, I'm having a great time learning how to Lisp!

While this isn't an answer to your particular programming question, and questions asking for tools are off topic for StackOverflow, if you're going to be doing HTML generation based on s-expressions, you might be interested in taking a look at CL-WHO, or some of the other Lisp markup language out there. — Joshua Taylor
– Joshua Taylor, Commented Sep 11, 2013 at 12:36
Yeah, I've been using some cl-who, but mostly lml2 and cl-html-parse. — gaauto
– gaauto, Commented Sep 12, 2013 at 3:05

Sylwester · Accepted Answer · 2013-09-11 00:26:29Z

4

How about two-list returns a list of elements you want to embed, like ((:H2 "header")(:P "paragraph")), then col1 could be defined as:

(defun col1 (content) `((:DIV :CLASS "col1") 
                              (:COMMENT " Column 1 start ")
                              ,@content ; goes here
                              (:COMMENT " Column 1 end ")))

(defun two-list () '((:H2 "header")(:P "paragraph")))

Notice that I removed the &rest from col1. If you want to still have that you need to do (apply #'col1 (two-list)) instead of (col1 (two-list))

answered Sep 11, 2013 at 0:26

Sylwester

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3 Comments

gaauto Over a year ago

Thanks, that did it. Your second solution works perfectly for me since I'd like to be able to add a bunch of stuff to the content area. Now off to read more about the @ symbol...

Joshua Taylor Over a year ago

@gaauto If Sylwester's answer works for you (and your comment indicates that it did), you should accept the answer to let others know that it worked for you.

m-n Over a year ago

If you look for documentation on an @ symbol you might have trouble finding it; the @ character has this particular meaning only in the context of the backquote and comma. lispworks.com/documentation/HyperSpec/Body/02_df.htm

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