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The eval and apply primitives

The implementation primitive eval of a Lisp systems is typically made available in the language, hereby providing access to evaluation of syntactical expressions (lists) in a given environment

The apply primitive is also available as a convenient mechanism for application of a function, in cases where all the parameters are available in a list

Expression

 Value

(let* ((ttl "My Document")
       (bdy (list 'p "A paragraph"))
       (doc
        (list 'html
         (list 'head
          (list 'title ttl))
         (list 'body bdy)))
      ) 
 (render (eval doc)))
 
<html>
 <head>
  <title>My Document</title>
 </head>
 <body>
  <p>A paragraph</p>
 </body>
</html>
(let* ((ttl "My Document")
       (bdy (list 'p "A paragraph"))
       (doc
        `(html 
           (head (title ,ttl))
           (body ,bdy))))
  (render (eval doc)))
 
<html>
 <head>
  <title>My Document</title>
 </head>
 <body>
  <p>A paragraph</p>
 </body>
</html>
(+ 1 2 3 4)
 
10
(+ (list 1 2 3 4))
 
Error: + expects argument of type number; 
 given (1 2 3 4)
(apply + (list 1 2 3 4))
 
10